THE 

PRODUCTION  AND  TREATMENT 
OF  VEGETABLE  OILS 


T.  W.  CHALMERS 

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THE   ENGINEER   SERIES 


THE    PRODUCTION    AND    TREATMENT 
OF    VEGETABLE    OILS 


■THE   ENGINEER   SERIES 


THE 

PRODUCTION    AND    TREATMENT 
OF    VEGETABLE    OILS 

INCLUDING  CHAPTERS  ON  THF,  REFINING  OF  OILS,  THE 
HYDROGENATION  OF  OILS,  THE  GENERATION  OF 
HYDROGEN,  SOAP  MAKING,  THE  RECO\'ERY  AND 
REFINING  OF  GLYCERINE,  AND  THE  SPLITTING  OF  OILS 

*^ 

T.   W^  CHALMERS,   B.Sc,   A.M.I.Mech.K. 

(On  the  Editorial  Staff  of  "The  Engineer") 

WITH  NINE   FOLDING  PLATES  AND 
95     ILLUSTRATIONS    IN    THE    TEXT 


LONDON 

CONSTABLE   &  COMPANY'  LTD 

10-12    ORANGE    STREET    LEICESTER   SOUARE  WC  2 

1920 


NEW  YORK 

D.  VAN  NOSTRAND  COMPANY 

EIGHT  WARREN  STREET 


First  ritblished . 
lieprintcd  . 


litis. 
I'.Hit. 

1  '.ILM. 


Priiite'l  ill  dreat  Ilrilaiii. 


PREFACE 

In  this  volume  an  attempt  is  made  to  deal  with  the  production  and  treatment 
of  vegetable  oils  primarily  from  the  engineer's  point  of  view,  an  aspect  of  the  industry 
which  hitherto  has  received  in  print  scanty  consideration  as  compared  with  the 
attention  paid  to  the  chemist's  side  of  the  matter. 

Everything  connected  with  the  recovery  and  treatment  of  vegetable  oils  has 
received  a  great  stimulus  from  the  conditions  brought  about  by  the  war.  The  indu.stry 
is  spreading  or  showing  signsof  spreading  in  many  directions,  and  great  as  its  importance 
in  this  country  has  been  in  the  past,  it  is  safe  to  prophesy  that  in  the  immediate  future 
it  will  be  greatci'  still.  It  is  hoped  that  this  volume  will  do  something  towards  assisting 
those  interested  or  lilcely  to  become  interested  in  the  industry  to  understand  the 
construction  and  working  of  the  principal  machines  and  plant  which  it  depends  upon. 
Sufficient  information,  it  is  believed,  is  given  regarding  the  chemical  and  commercial 
aspects  of  the  matter  to  make  the  book,  although  written  from  the  engineer's  standpoint, 
a  more  or  less  general  treatise  on  the  vegetable  oil  industry. 

The  chapters  which  follow  originally  appeared  as  a  series  of  articles  *  in  The. 
Engineer.  In  planning  this  series  it  was  at  one  time  hoped  to  include  in  it  sections 
devoted  to  certain  aspects  of  the  industrial  employment  of  vegetable  oils,  notably  on 
the  employment  of  such  oils  in  the  manufacture  of  linoleum  and  margarine.  While 
there  is  much  of  engineering  interest  in  both  these  branches  of  industry  it  \\'as  found 
that  a  consideraljle  degree  of  secrecy  was  preserved  regarding  the  machinery  employed 
in  the  former,  while  the  machinery  for  the  latter  came  almost,  if  not  quite,  exclusively 
from  abroad,  notably  from  Holland.  The.se  reasons  and  the  exigencies  of  space, 
compelled  a  considerable  restriction  in  the  account  of  the  industrial  employment  of 
vegetable  oils. 

On  the  other  hand,  much  valuable  infornu^tion  was  obtained  regarding  certain 
aspects  of  the  production  and  treatment  of  vegetable  oils,  much  of  which  infornuition, 
it  is  believed,  has  not  hitherto  been  published,  or  has  been  published  in  an  inaccurate, 
out-of-date,  or  incomplete  form.  In  this  connection  special  attention  may  perhaps 
be  directed  towards  the  sections  dealing  with  the  extraction  of  oils  by  means  of  chemical 
solvents,  oil  refuiing,  oil  hardening  and  the  generation  of  hydrogen,  the  recovery  and 
refining  of  glycerine,  and  the  splitting  of  oils. 

Sincere  thanks  are  due  to  all  those  who  so  courteously  afforded  their  assistance 

in  the  preparation  of  the  original  series  of  articles,  particularly  to  -Messrs.  Manlove, 

AUiott  &  Co.  :  to  Mr.  H.  J.  Pooley,  of  Messrs.  George  Scott  k  Son  ;  and  to  Mr.  Howard 

Lane. 

T.    W.    C, 

London, 

July,  1917. 

•  "The  Production  anil  Indu-strial  ICniploynicnt  of  y^cgetiible  Oils."  Kifiliteen  arlii'lcs. 
Pol)ni;iry  9tli   to  June  2'Jth,    1'JI7. 


11356 


CONTENTS 


CHAPTER    I. 
Imtroductory  a>ji)  General        ...........  1 

CHAPTKU    II. 
The  rinxciPAi,  Vf.grtable  Oil?  ..........         0 

CHAPTER    III. 
Prepauatoky  .Machinery   for  Copra  an'd  Linseed      .  .  .  ...  .  .12 

(CHAPTER    IV. 
Preparatory  .Machinery  ior  Palm  Fruit  ano  Palm  Kiornels  .....       21 

CHAPTER   Y. 
Preparatory  Machinery  for  Cotton  Seer  and  Castor  Seed    .....        29 

CHAPTER    VI 
Some  Special  Forms  ok  REDucriox   Maciiinhry.  .......       39 

CHAPTER    VII. 
.Meal  Kettles,  Receiving  Pans  axd  Moulding  Machines.  .         .         .         ...       46 

CHAPTER    VI II. 
Oil  Presses  —Anglo-American  Type  ..........       56 

CH.APTER    IX. 
Oil  Presses — Cage  Type    ............       62 

CHAPTER    X. 
The  General  Arrangement  of  Oil  Mills.  ........        73 

CHAPTER    XI. 
Extraction  oi'  Oils  by  Chemical  Solvents        ........       83 


CHAPTER    XII. 
The  Refining  of  Oils         ............       93 

CHAPTER    XIII. 
The  Hydrogen ation  or  Hardening  of  t)iLs       .  .  .  .  .  .  .  .106 

CHAPTER  XIV. 
The  Generation  ov  Hydrogen  for  Oil  Hardening  Purposes  .  .  .  .  .113 

ClhVPTER  XV. 
The  Manufacture  of  Soap  .  .  .  ■  •  •  •  •  .122 

CHAPTER  XVI. 
Glycerine  Recovery  and  Refining  and  the  Splitting  of  Oils        ....      132 

Index •  I*'-' 


LIST    OF    ILLUSTRATIONS 


s. 

4. 

5. 

6. 

7. 

8. 

i). 
10. 
11. 
12. 
Ki. 
U.  , 
15.  \ 
16. 
17. 
18. 
10. 
20. 
21. 
22. 
23. 
24. 
25.. 
26. 
27. 
28. 
2». 
30. 
31. 
32. 
33. 
34. 
3.'). 
36. 
37. 
38. 
38a. 
3!). 
40. 
41. 
42. 
43. 
44. 
45. 
46. 
47. 
48. 
49. 
50. 
51. 


Cocoa-nut  Splitting  Machine     . 

M.\GNETIC    SePAEATOK   FOR    COPEA,    ETC. 

Preliminary  Beeaking  Machine 

Shredding  and  Crushing  Rolls  foe  Copra,  etc 

Shredding  and  Crushing  Rolls 

Rolls  foe  further  Reduction  of  Copra    . 

Final  Reduction  Rolls      .... 

Screening  Machine  for  Linseed,  etc. 

Rolls  for  Linseed,  etc.     .... 

Palm  Fruit,  Peric.\rp,  Xuts,  Shells  and  Kern 

Bunch  of  Palm  Fruit  .  ,  .  . 

Faikf.vx's  Depericarping  Machine 

Depericaeping  Machine  for  Palm  Fnun     . 

Palm  Xut  Brushing  Machine      ... 

Palm  Nut  Cracking  and  Separating  Machine 
Palm  and  Palm  Kernel  Oil  Mill 
American  and  Egtpti.-vn  Cotton  Seed 
Cotton  Seed  De-linter       .... 

Cotton  Seed  Decorticating  Machine 
Castor  Seed — Pods,  Beans  and  Kernels   . 
Castor  Seed  Sheller  .... 

Castor  Seed  Decorticator  and  Sepae.\tor 
Castoe  Seed  Decorticator  and  Separator 
Castor  Seed  Decorticator  and  Separator 
Horizontal  Seed  Rolls      .... 

Edge  Runner      ...... 

Special  Grinding  Mill  with  Concave  Pl.\tes 
Reducing  Mill  and  Cake  Breaker    . 
Disintegrator      ...... 

Disintegrator,  showing  Beater  Ar.ms,  Waved 
Meal  Kettle       ...... 

Double  Kettle  ...... 

Kettle  and  Moulding  Machine 
Receiving  Pan  and  Moulding  Machines    . 
Ordinary  Form  of  Hydraulic  Moulding  Machine 
Special  Form  of  Hydraulic  Moulding  Machine 

!  Se.mi-automatic  Moulding  Maciune 

Battery  of  Four  Anglo-American  Presses 
Small  Anglo-American  Press,  etc.     . 
Two  Small  Cage  Presses    .... 

Cage  Press  and  Kettle  in   a  .Mill 

Twin  Cage  Presses     .  .  . 

Twin  Cage  Presses     ..... 

Battery  ok  Four  Cage  Presses 
Revolving  Cage  Press        .... 

Cross-section  of  a  Mill  with  Anglo-.V.merican  Presses 
Plan  ok  Mill  with  Cage  and  Anglo-American  Presses 
High  ani)  Low-pressure  Oil  Press  Pump  . 
Oil  Press  Pump  ...... 

Oil  Mill  Accumulators      .... 


Facing 


LIST   OF   ILLUSTRATIONS 


.">2.  ACCCMI'LATOK^    IX    AX    OlL    MlLL 

^>'^.  acccmcxatok  pcmp     . 

54.  Relief  Valve  Detail? 

o5.  Cake-paring  Machixe. 

56.  Htukaflic  Cake-pakixg  Machlse 

57.  Bexzese  Solvext  Extractiox  Plaxt 

58.  ."^COTT    SOLVEXT    EXTRACTOR    WITH    AGIT.ITIXG    GEAII 

59.  .<cOTT  Solvent  Extractor  without  Agitatixg  Gear 

60.  ."^MALL  Solvent  Plant  .... 

61.  Filter  I^ress  f<>r  Oil  .... 

62.  Filter  Press  Plate  .... 

63.  Two  Forms  of  Filter  Plates'     . 

64.  Washing  Machixe  for  Filter  Cloths 

65.  Centrifugal  Extractor  for  "  Foots  " 

66.  Cotton  Seed  Oil  Refixert 

67.  Vacuum  P-\x  axd  Condenser 

68.  Cocoa-nut  On,  Rehnert     .... 

69.  Stearixe  Presses  for  Demaegarixatixg  Oil 

70.  Plax  of  Oil  Htdrogexisixg  Factory  ......         Facing 

71.  Eaxe  Autoclave 
Mr.  Howard  Laxe's  Experimental  OrL-HARDEXiXG  Plaxt 

73.  Diagram  of  the  Lane  Htdrogex   Retort  Furnace 

7-1.  Three-wat  Reversixg  Cock  for  Htdrogex   Retort  Furnace 

Experimental  Htdrogen  Plant 

Soap  Kettle 

Crutciiing  Machine     . 

78.  Twix  Crutchixg  Machixe? 

79.  Steam  Driven"  Crutcher 

80.  Soap  Frame 

81.  Slab  Cuttixg  Machixe 

82.  Bar  Ccttdcg  Machixe 

83.  .Soap  Drtixg  Plant 

84.  Stamping  Machine 

85.  Chipping  Machine 

86.  Milling  Machixe 

87.  Soap  Squeezing  Machine  or  Plodder 

88.  Single-effect  Vacuum  Evapc>rator  for  Concemratixg  Crude  Gltcerixe 

89.  Single-effect  Vacuum  Evaporator  for  Concextratixg  Crude  Gltcerfne 

90.  Removing  Salt  from  a  Vacuum  Evaporator 

91.  .\uTOMATic  Salt  Discharging  Device 

92.  Four  Dourle-effect  Vacuum  Evaporators  for  Treatixg  500  Toxs  of  Soap  Lte5 

per  Dat         ........... 

93.  Double-effect  Vacuum  Evaporator  for  Concentrating  Crude  Gltcerin 

94.  Oil  .4ND  Fat  Splitting  Autoclaves       ....... 

95.  Plant  for  Splitting  Oii.s  and  Fats  bt  the  TwrrcHEU.  Process  142 

96.  (iLTCERINE    RefIXTNG    AXD   CONCEXTRATIXG    PlaXT 

97.  IXTERIOR    OF   A    GlTCERIXE    ReFIXERT     . 


PAGE 

78 


94 

95 

95 

96 

97 

98 

loo 

102 

IU4 

108 

no 
111 

lit; 

)  iv 

123 
124 
125 
126 
126 
127 
127 
12s 
li» 
12;' 
12'.' 
]:><> 
134 
135 
136 
136 

138 
139 

140 
143 
145 
146 


LIST    OF    PLATES 


I'LATE 

I.  400-TOK  AngloAmekkan   Hydraulic   Oil  Press     .           .  .            Facing  page  5C 

II.  Cage  Type  Oil  Press         .          .          .          .           .          .  ..,,,.  62 

III.  Revolving  Cage  Type  Oil  Press          .           .           .           .  •         .         ,,         „  69 

IV.  Copra  Oil  Mill  with  Cage  Type  Presses     .           .           .  ...,.,  75 

V.  Benzene  Solvent  Extraction  Plant  for  Vegetable  Oils  .         .         „         „  87 

VI.  Oil-Hardening  Autoclave  and  its  Details           .           .  .....  Ill 

VII.  TiiF.  Hardening  of  Oils^Tiie  Lane  Hydrogen   Retort  Flrnace  .         ,,         ,,  115 


CHAPTER  I 
INTRODUCTORY  AND  GENERAL 

'J'heke  are  three  distinct  systems  or  methods  whereby  oils  in  general  can  be 
classified  into  groups.     These  may  be  called  the  popular,  the  scientific,  and  the  practical. 

The  popular  sy.stem  divides  them  into  animal,  vegetable,  and  mineral  oils  according 
to  the  natural  Idngdom  from  which  they  are  derived.  This  scheme  of  classification  has 
little  scientific  value,  for  it  is  more  than  doubtful  if  we  are  ever  justified,  scientifically, 
in  speaking  of  a  "  mineral  "  oil.  It  is  practically  established  that  oil  is  always  an 
organic  and  never  an  inorganic  substance,  and  that  so-called  minei'al  oil,  whether 
obtained  direct  from  a  well,  or  recovered  by  distilling  shale,  is  merely  the  transformed 
product  of  animal  or  vegetable  organisms.  Nevertheless  "  mineral  "  oil  is  so  distinct 
in  its  properties  from  either  vegetable  or  animal  oil  proper  that  in  most  practical 
circumstances  its  separate  classification  is  highly  desirable.  In  popular  phraseology, 
it  may  be  remarked,  "  mineral  "  oil  means  petroleum,  the  raw  product,  or  one  of  the 
substances  derived  from  it  by  treatment.  It  is  not  usual  to  speak  of  the  coal  tar  oils 
as  "  mineral  "'  oils,  although  the  well-established  position  of  coal  as  a  mineral  would 
certainly  justify  us  in  doing  so. 

The  second  scheme  of  classification  is  the  chemical.  Into  this  we  do  not  projiose 
to  enter  here,  for  its  interest  is  at  present  almost  purely  scientific. 

The  third  or  practical  system  classifies  oil  primarily  into  two  groups,  namely, 
essential  oils  and  fixed  oils.  An  essential  oil  is  one  which  can  be  volatilised  without 
decomposing  it.  A  fixed  oil  is  one  which  cannot  be  so  volatilised.  The  fixed  oils  are 
further  subdivided  into  two  groups,  the  mineral  oils  on  the  one  hand  and  the  fatty  oils 
on  the  other. 

Essential  oils,  as  we  have  said,  are  distinguished  by  the  fact  that  they  can  be 
distilled  without  suffering  an  alteration  in  their  chemical  composition.  They  are 
obtained  entirely  from  vegetable  sources,  commonly  by  distilling  the  leaves,  flowers, 
fruit,  or  seeds  of  various  plants.  Certain  barks  and  roots  also  yield  essential  oils,  as 
do  amber  and  other  resinous  exudations  from  trees.  Distillation  is  not,  however, 
universal,  mechanical  processes  and  extraction  by  means  of  .solvents  being  sometimes 
adopted.  Essential  oils  ai-e  u.sed  for  many  minor  purposes.  Thus  the  oil  distilled 
from  pine  needles  finds  employment  in  the  manufacture  of  boot  polishes,  while  cedar- 
wood  oil,  on  account  of  its  high  refractive  index,  is  in  demand  for  microscopic  purposes. 
(Jeneially  speaking,  however,  these  oils  may  be  said  to  be  in  chief  use  as  perfumes,  as 
flavourings,  and  as  medicines,  typical  examples  of  the  three  classes  being  lavender 
oil,  peppcnnint  oil,  and  eucalyptus  oil. 

Fixed  oils,  as  already  remarked,  cannot  be  distilled  without  suffering  chemical 
decomposition,  and  are  divided  into  two  gi'oups,  the  muieral  and  the  fatty.  The 
mineral  group  comprises  petroleum  and  its  derivatives,  and  is  identical  with  the 
mmeral  group  of  the  popular  classification.  The  fatty  oil  group,  on  the  other  hand, 
is  not  identical  with  the  animal  oil  group  of  that  classification,  although  it  is  generally 
true  that  all  animal  oils  are  fatty  oils.  Many  fatty  oils,  we  might  even  saj'  the  most 
important  fatty  oils,  are  of  vegetable  origin.  Certain  of  the  heavier  mineral  oil  deriva- 
tives may  look  like  fatty  oils,  and  are  used,  as  are  some  fatty  oils,  for  lubricating  and 


2  THE   PRODUCTION   AND   TREATMENT   OF   ^T:GETABLE   OILS 

burning  purposes.  Nevertheless  the  two  classes  are  radically  different  in  their  cliemical 
composition.  The  broad  and  most  important  and  practical  difference  between  them 
lies  in  the  fact  that  fattj-  oils  can  be  converted  into  soaps  by  acting  upon  them  witli 
caustic  alkalis  and  otiier  inorganic  substances,  whereas  mineral  oils  cannot  be  saponified. 

Fatty  oils  are  thus  either  of  vegetable  or  animal  origin.  Neither  "  vegetable  " 
nor  "  animal,"  as  here  used,  is.  of  course,  to  be  interpreted  in  a  restricted  sense. 
Speaking  botanically,  very  few  oils  are  obtained  from  vegetables,  the  only  one,  in 
fact,  which  conies  readily  to  mind  being  that  derived  from  radishes,  the  seeds  of  which 
yield  an  oil  of  the  rape  cr  colza  type.  The  majority  of  and  the  most  important  vege- 
table oils  are  extracted  from  the  seeds  of  plants,  for  example,  linseed,  cotton  seed, 
rape  seed,  hemp  seed,  poppy  seed,  and  smaflower  seed.  Important  vegetable  oils  are 
also  obtained  from  the  nuts  of  certain  trees,  such  as  the  wabiut.  cocoa-nut.  and  hazel 
nut.  Other  trees  yield  oils  from  their  fruit,  either  from  the  fruit  itself .  as  in  the  case 
of  olive  oil.  or  from  the  fruit  kernels,  as  in  the  case  of  cherry,  apricot,  plum,  peach  and 
palm  kernel  oils. 

Speakmg  zoologically,  the  term  "  animal  oil  "  is  more  or  less  justified.  Thus  the 
sheep,  the  horse,  the  ox,  the  whale,  the  seal,  and  the  porpoise  are  all  animals  and  jaeld 
important  oils.  It  may  perhaps  be  remarked  parenthetically  that  the  hoof  of  the  ox 
is  the  soui'ce  of  the  well-knowai  neats  foot  oil,  and  that  from  the  jaw  of  the  porpoise 
there  is  obtained  a  veiy  valuable  oil  used  for  lubricating  watch.es  and  other  delicate 
machinery.  It  must  be  admitted,  however,  that  some  important  "'  animal  "'  oils  are 
recovered  from  fish,  notabh'  from  the  livers  of  fish.  Such  oils  find  employment  chiefly 
in  currying  leather,  to  some  extent  in  soap  making,  and  to  a  small  degi-ee  in  medicine. 
The  birds  also  su])ply  "  animal  "  oils  or  fats.  Thus  the  egg  of  the  common  hen  yields 
an  oil  used  in  leather  dressmg.  while  fats  are  obtained  from  tl:e  blackcock,  duck,  and 
goose.  Even  the  reptile  kingdom  is  drawai  upon,  foi'  tl:e  rattlesnake  gives  a  fat  which 
is  used  in  pharmacj'.  So  far  as  we  laiow  the  insect  kuigdom  is  not  used  as  a  source 
of  "  animal  "  oil.  This  is  so  presumabty  because  of  the  difficulty  of  collecting  insects 
in  quantities  sufficient  for  treatment,  and  because  of  the  difficulty  of  treating  them. 
It  is  certainly  not  due  to  the  absence  of  oil  in  their  composition.  Thus,  cochineal 
extracted  with  benzene  can  be  made  to  yield  an  oil.  Cochineal  is,  of  course,  the  dried 
bodies  of  an  insect  which  lives  on  a  species  of  cactus  cultivated,  for  the  sake  of  the 
insect,  in  Mexico  and  Central  Ameiica. 

Vegetable  and  animal  oils  are  frequently  closely  similar  in  composition  and 
behaviour.  Until  recently  it  was  in  general  impo.ssible  to  determine  to  which  class  a 
given  oil  belonged  solely  by  chemical  examination.  Means,  however,  are  now  available 
for  discriminatmg  chemically  between  the  two  classes.  Thus,  animal  oils  contain  a 
certain  alcohol  laiown  to  the  chemist  as  cholesterol.  This  body  can  be  isolated  from 
the  oil  recovered  from  sheep's  wool,  and  is  well  kno\\Ti  to  the  general  public  under  the 
name  of  lanolm.  A  similar  alcohol  is  contained  in  vegetable  oils.  This  body  is  known 
as  phytosterol.  It  appears  to  have  the  same  molecular  formula  as  cholesterol,  but 
mider  certain  ciicumstances  it  behaves  different]}'.  Thus  under  the  microscope  the 
crystals  of  the  two  bodies  are  foimd  to  be  of  different  shape.  This  and  the  fact  th.at 
their  acetates  melt  at  different  temperatures  form  a  basis  for  di.stinguishing  chemically 
between  a  vegetable  and  an  animal  oil. 

Apart  from  the  existence  of  these  two  bodies  in  animal  and  vegetable  oils  respec- 
tively, the  chemical  composition  of  such  oils  cannot  be  regarded  at  present  as  being 
complete!}^  understood.  This  composition,  of  course,  varies,  and  varies  greatly,  from 
oil  to  oil.  Further,  although  to  a  lesser  extent,  it  varies  in  any  one  oil  accordmg  to 
the  soil  and  climate  in   which  the  plant  from   which   it  was  derived  was  grown. 


INTRODUCTORY    AND    GENERAL  3 

or  according  to  the  age,  food,  even  the  personal  habits,  of  the  animal  from  which  it 
was  obtamed.  There  need  therefore  be  little  wonder  if  the  classification  of  oils  on 
a  chemical  basis  is,  as  we  have  stated  it  to  be,  a  matter  at  present  almost  solely  of 
scientific  interest.  Even  in  the  matter  of  definmg  what  an  oil  in  general  is  the  chemist 
cannot  do  more  than  adopt  the  popular  description  of  an  oil  as  a  substance,  usually 
liquid  at  ordinary  temperatures,  which  is  insoluble  in  water,  combustible,  and  more 
or  less  viscous.  This  deflniticn  succeeds  in  that  it  excludes  oil  of  vitriol — the  popular 
term  for  concentrated  sulphuric  acid — from  among  the  oils.  It  fails  only  in  so  far  as 
it  does  not  distinguish  between  an  oil  and  a  fat.  There  is  no  chemical  distinction 
between  a  fatty  oil  and  a  fat.  It  is  purely  a  matter  of  temperature,  for  a  fatty  oil 
when  frozen  becomes  a  fat,  and  a  fat  %\hen  melted  becomes  a  fatty  oil.  A  particular 
instance  of  how  climate  affects  the  nomenclature  is  to  be  found  in  the  case  of  cocoa-nut 
oil.  In  Lidia  this  substance  is  liquid,  and  is  therefore  to  be  regarded  as  an  oil.  In 
this  country  it  is  usually  solid  and  should  properly  be  spoken  of  as  a  fat.  It  has  been 
proposed  to  adopt  20'  C.  as  the  standard  temperature  at  wliich  to  judge  fats  and  oils. 
The  hardest  fats,  it  may  be  added,  melt  at  about  50°  C,  while  some  oils  are  still  liquid 
at  and  below  the  freezing  point  of  water. 

As  the  title  of  this  volume  indicates,  we  propose  to  describe  and  discuss  the 
production  and  treatment  of  vegetable  oils.  It  is  not  our  mtention  to  deal  with  either 
essential,  mmeral  or  animal  oils.  The  whole  field  is  too  vast  to  be  treated  conve- 
niently in  one  volume,  and,  moreover,  is  not  sufificiently  well  connected  to  have  a 
common  interest.  Li  fastenmg  our  attention  upon  vegetable  fatty  oils  considerations 
other  than  these  have  also  weighed  with  us.  Among  such  considerations  may  be 
mentioned  the  fact  that  these  oils,  particularly  those  suitable  for  edible  purposes, 
are  now  attracting  attention  in  this  country  to  an  extent  hardly  contemplated  before 
the  war.  As  is  well  laio\\ii,  Germany  had  in  recent  years  become  a  very  formidable 
rival  to  this  coimtry  in  its  command  over  the^vegetable  oil  industries,  and  had,  as  in 
Nigeria,  for  example,  secured  virtual  monopolies  over  certain  of  the  raw  materials. 
These  sources  of  supply  have  now  been  largely  set  free  and,  let  us  hope,  will  never 
again  pass  into  our  enemies'  hands.  Then  agaui  the  war  has  led,  as  most  of  us  laiow 
from  experience,  to  an  enormous  increase  in  the  demand  for  margarine,  a  very  impor- 
tant outlet  for  certam  varieties  of  fatty  vegetable  oils.  Although  much  of  this  substi 
tute  for  butter  still  comes  from  Holland,'  efforts  on  a  gratifying  scale  are  being  made  to 
meet  the  demand  witii  margarine  produced  in  this  country. 

Aparti  from  the  margarine  industry,  the  fatty  vegetable  oils  constitute  the  raw 
product  or  one  of  the  raw  products  of  several  important  industries.  Thus  they  are 
used  hi  the  manufacture  of  paints  and  vaniishes,  soap  and  candles,  linoleum  and 
oilcloth.  In  these  industries  the  engineer  plays  a  veiy  considerable  part,  so  that  both 
in  the  production  and  in  the  industrial  employment  of  vegetable  oils  much  of  great 
engmeering  interest  is  to  be  found.  It  is  from  the  engmeerhig  standpomt,  and  in 
particular  from  the  British  engineer's  standpomt,  that  we  propose  chiefly  to  regard 
the  matter. 

In  the  next  chapter  we  shall  discuss  the  sources  from  which  the  better  known 
vegetable  oils  are  obtained,  and  the  principal  uses  to  which  they  are  put.  For  the 
present  it  will  be  u.seful  to  describe  without  going  into  details  the  general  methods 
adopted  in  their  production. 

There  are  two  broad  methods  of  extracting  fatty  oils  from  vegetable  products — 
one,  that  employmg  pressure,  being  purely  a  mechanical  process,  and  the  other,  that 
extracting  the  oil  by  means  of  solvents,  being  more  or  less  a  chemical  process.  Under 
the  first  method  the  seed,  if  small,  is  simply  crushed  in  a  hydraulic  press.     The  oil 


4  THE   PRODUCriOX   AND   TREATJIENT   OF  VEGETABLE   OILS 

forced  out  of  the  seed  is  caught  and  drained  off.  If  the  seed  is  large  or  if  the  raw 
material  is  copra  or  some  such  stuff,  it  is  first  giound  up  in  special  machmes  before 
being  crushed.  The  seed  or  seed  "  meal  "  is  sometmies  heated  during  the  process  of 
crushing.  The  oil  then  produced  is  known  as  '"  hot  pressed  '"  or  "  hot  drawn  "  oil. 
Such  oil,  however,  is  apt  to  be  unduly  discoloured  by  reason  of  its  having  dissolved 
from  the  seed  dm-ing  expression  an  excessive  amoiuit  of  colouring  matter.  For  certain 
purposes,  therefore,  notably  for  edible  purposes,  "  cold  drawii  ""  oil  is  preferred.  The 
"  cold  drawing  ""  process  usuallj'  leaves  quite  a  considerable  quantity  of  oil  remaining 
behmd  in  the  seed.  Consequently  it  is  a  common  practice  to  break  up  the  cake  left 
in  the  press  after  cold  drawmg,  heat  it  and  extract  a  "  second  expression  oil "'  bj'  the 
hot  process.  The  cake  left  may  be  once  again  broken  up,  heated,  and  expressed  a 
tliird  time,  but  even  so  it  is  scarcely  possible  to  extract  more  than  90  to  95  per  cent, 
of  the  total  oil  in  the  seed  by  the  crushing  process  alone. 

The  second  process  extracts  the  oil  from  the  seed  or  seed  meal  by  means  of  chemical 
solvents,  the  seed  being  treated  either  hot  or  co!d^  The  three  cliief  solvents  in  use  are 
^  benzene,  carbon  disulphide,  and  carbon  tetrachloride.  The  process  in  outline  consists 
of  aUowi:ig  the  solvent  to  percolate  through  the  seed  or  meal  in  a  closed  vessel,  draining 
off  the  solvent  and  dissolved  oil,  transferrmg  it  to  a  heated  still  and  there  driving  off 
the  volatile  solvent  so  as  to  leave  the  oil  behind.  The  solvent  is  condensed  and  re-used. 
So  far  as  the  percentage  of  oil  recovered  from  the  seed  is  concerned,  this  process 
is  distinctly  superior  to  the  pressure  process,  for  under  it  as  much  as  99  per  cent,  oi 
the  oil  can  readily  be  extracted  from  the  raw  material.  A  further  advantage  of  the 
process  undoubtedly  lies  in  the  simplicitj-  and  cheapness  of  the  plant  required  as 
compared  with  that  used  under  the  pressure  method. 

The  relative  advantages  of  these  two  processes  form  a  subject  of  much  discussion. 
As  the  reader  is  doubtlessly  aware,  the  residue  left  after  the  oil  has  been  extracted  from 
linseed,  cotton  seed,  copra,  and  certain  other  oil-bearing  substances,  is  in  great  demand 
as  a  cattle  food.  While  it  is  admitted  generally  that  the  solvent  extraction  process 
recovers  the  oil  more  thoroughly  from  the  seed,  etc.,  than  does  the  pressure  process, 
it  is  frequently  urged  that  its  verj'  efficiencj'  in  this  respect  deprives  the  residue  of 
much,  if  not  quite  the  whole  of  its  value  as  a  feeding  stuff.  The  5  to  10  per  cent, 
of  oil  remaming  in  the  cake  left  after  crushing  in  a  press  is  not.  it  is  claimed,  a  source 
of  loss,  for  without  it  the  residue  could  at  best  command  a  market  only  as  manure. 
On  the  other  hand,  it  is  stated  that  the  oil  left  in  the  cake  is  only  a  heat- 
forming  substance,  and  that  the  husks,  etc.,  of  the  seed  foj"m  the  real  food  value  of 
the  cake.  Further,  oil  press  cake,  it  is  argued,  cannot  be  fed  imdiluted  to  cattle, 
but  has  to  be  mixed  with  bran  and  other  substances,  a  fact  which  would  seem  to 
imply  that  oil  cake  is  a  richer  food  than  it  need  be.  The  residue  left  by  the  solvent 
extraction  process  retains  all  the  hu.sks,  etc.,  wliile  its  richness  in  oil  is  not  such  as  to 
prevent  its  being  fed  directly  to  cattle. 

Whatever  maj-  be  the  true  way  of  looking  at  this  matter  we  have  next  to  note 
that  the  advocates  of  the  pressure  system  urge  a  further  objection  to  the  solvent 
extraction  process.  This  is  to  be  fomad  in  the  alleged  difficulty  o  ■  impos.sibihty  of 
getting  rid  of  the  last  traces  of  the  solvent  used  eitl.er  from  the  oil  or  the  residue. 
The  point  is  of  importance,  for  the  solvents  commonly  used  are  either  poisonous  or 
have  a  nauseous  taste.  If  the  allegation  were  well  fomided,  therefore,  solvent  extracted 
oils  could  not  be  readily  used  for  edible  purposes,  and  would  have  to  find  an  outlet 
solely  in  industrial  appUcations,  such  as  soap  making,  while  the  residue  would  probably 
be  refused  as  food  by  cattle  and  would  have  to  be  used  as  manure. 

Whatever  may  at  one  time  have  been  the  case,  and  may  still  be  where  old-fasliioneil 


INTRODUCTORY    AND    GENERAL  5 

Germ  an -made  solvent  extraction  plant  is  in  use,  it  seems  certain  that  recent  progress 
has  overcome  these  objections  to  the  process.  We  are  credibly  informed  that  horses 
and  cattle  will  eat  extracted  meal  with  avidity.  AVe  have  examined  oil  extracted 
with  benzene,  and  neither  to  the  taste  nor  smell  did  it  reveal  any  trace  of  the  solvent, 
although  benzene  is  said  to  be  the  most  difficult  of  all  the  solvents  to  elimmate. 

It  is  advisable,  we  think,  to  discard  the  idea  that  the  two  processes  ai'e  essentially 
rivals.  It  is  certainly  undoubted  that  they  can  be  very  profitably  worked  side  by  side 
in  the  same  mill,  for  the  solvent  process  can  be  made  to  supplement  the  pressure 
process  frequently  with  great  advantage.  Thus  certain  seeds  can  profitably  be  crushed 
to  recover  a  high-class  edible  or  other  oil,  and  thereafter  treated  with  .solvents  to  recover 
the  remaining  oil.  It  is  to  be  noticed  tl  at  in  discussing  the  relative  advantages  of  the 
two  processes  it  is  not  wise  always  to  confine  our  argument  to  the  general  case.  Oui 
conclusions  must  be  modified  not  only  by  local  conditions  as  to  the  outlet  for  the  oil 
and  seed  residue — that  is,  the  press  cake  or  extracted  meal — but  also  by  the  particular 
oil-bearing  seed  which  is  to  be  treated.  Thus  the  residue  of  certain  seeds,  rape  seed, 
for  example,  has  little  or  no  value  as  a  foodstuff  however  it  is  obtamed.  It  seems, 
therefore,  only  reasonable  in  such  ca.ses  to  adopt  that  process  which  recovers  most  oil 
from  the  seed,  and  which,  moreover,  leaves  the  residue  in  a  form  which  is  directly 
suitable  for  manurial  purposes.  On  the  other  hand,  the  solvent  extraction  process 
should  be  studied  cautiously  if  castor  seeds  are  in  question.  Castor  oil  is  in  several 
respects  an  exceptional  oil  and  appears  to  suffer  some  chemical  change  by  the  action 
of  solvents. 

In  conclusion,  it  may  be  remarked  that  any  objection  to  solvent  extracted  meal 
as  a  foodstuff  on  the  ground  that  it  is  deficient  in  oil  can  be  overcome  by  mixing  it 
with  the  desired  proportion  of  oil  and  moulding  it  into  cakes.  Again,  it  can  be  mixed 
with  gromid-up  press  cake  and  the  whole  remoulded.  Both  practices  are  followed  on 
the  Continent.  We  may  add  that  so  far  as  we  can  discover  there  is  no  ground  for  the 
assertion  made  in  an  authoritative  work  that  extracted  meal  cannot  be  sold  in  this 
country  as  a  cattle  food. 


CHAPTER   II 

THE   PRINCIPAL  VEGETABLE   OILS 

It  is  not  quite  easy  to  compile  a  list  which  is  likely  to  meet  with  imiversal  approval 
as  representing  the  principal  vegetable  oils.  In  presenting  the  following  brief  summary 
of  the  sources,  characteristics,  and  chief  uses  of  certain  oils,  we  will  therefore  not  insist 
upon  its  being  a  complete  li.st  of  the  principal  vegetable  oils.  It  may  be  taken,  however, 
that  all  the  oils  mentioned  are  of  first-class  or  of  considerable  industrial  importance. 

Linseed  Oil. 

Few,  we  think,  will  quarrel  ■nith  our  selection  or  this  oil  for  notice  before  all  others. 
It  is  midoubtedly  one  of  the  most  important,  if  not  the  most  important,  oil  known 
to  man. 

The  flax  plant  is  a  herb  consisting  of  a  single  stem  20  to  40  inches  high,  and  is 
widely  cultivated  in  many  temperate  climates,  notablj^  in  Ireland,  Belgium.  Holland, 
France,  Rus.sia,  India,  Canada,  the  United  States,  and  the  Argentine.  Its  stem 
consists  of  a  core,  an  outer  covering,  and  an  intermediate  layer  of  tissue  kno\Mi  as 
the  "  bast."  The  bast,  suitably  separated  from  the  other  parts  of  the  stem,  fonns, 
of  course,  the  basis  of  the  linen  industry.  The  fruit  of  the  plant  yields  a  seed,  "  linseed," 
which  forms  the  basis  of  the  linseed  oil  industry.  The  plant  is  cultivated  in  two 
distmct  forms,  one  more  richly  flowered  than  the  other,  and  therefore  gi-o^\ii  tor  the 
sake  of  its  seeds.  This  varietj'  is  chiefly  cultivated  in  Russia,  India.  Canada,  the 
United  States,  and  the  Argentine.  The  Russian,  and  particularly  that  coming  from 
the  Baltic  districts,  is  perhaps  the  mo.st  highly  esteemed  source  of  linseed  oil.  The 
seed  contains  from  38  to  40  per  cent,  of  oil. 

The  oil  is  recovered  from  the  seed  very  commonly  by  hot  pressing.  The  hot 
press  cake  retains  about  10  per  cent,  of  oil  and  forms  an  extremely  valuable  and 
wholesome  cattle  food.  Occasionally,  the  seeds  are  pressed  cold  for  the  recovery  of 
an  edible  oil.  The  hot  pressed  oil  is  of  v,ic\e  application  in  the  arts.  It  is  used  exten- 
sively in  the  manufacture  of  soft  soaps.  Its  high  specific  gravity  and  its  fine  drying 
qualities  make  it  of  first  importance  in  the  manufacture  of  paints  and  vaniishes. 
The  chemical  changes  which  occur  when  linseed  oil  "  dries  "  are  not  clear,  but  it  is 
certain  that  the  main  feature  is  the  oxidation  of  the  oil.  The  oxygen  is  taken  up 
rapidty  and  transforms  the  oil  into  a  flexible  solid  mass,  lcno\\ii  as  .solidified  or  oxidi.sed 
lin.seed  oil  or  as  "  linoxyn."  This  substance  is  manufactured  on  a  large  scale,  for  it  is 
the  principal  raw  material  of  the  linoleum  and  oilcloth  industry.  Linseed  oil  in  the 
natural  state  dries  to  an  elastic  .skin  in  about  three  days.  If,  however,  it  is  prepared 
by  heating  it  with  various  salts  of  lead  or  manganese,  it  Avill  dry  within  six  or  eight 
hours.  So  treated,  it  is  known  as  "  boiled  "  oil  and  is  much  used  by  painters  and 
artists.  Heated  with  sulphur,  linseed  oil  is  used  medicinally.  Acted  upon  otherwise 
by  sulphur  or  by  chloride  of  sulphur  the  oil  solidifies  into  a  vulcanised  oil,  which  is 
used  as  a  substitute  for  rubber.  This  material  is  chiefly  used  as  an  addition  to  genuine 
raw  rubber. 

That  the  one  plant  should  give  us  so  many  and  .such  different  materials  is  a 
remarkable  illustration  of  Nature's  economy.     The  picture  would  be  complete  were 


THE    PRINCIPAL    VEGETABLE    OILS  7 

linseed  oil  available  for  burning  and  lubricating  pui-poses.     Its  quick  drying  properties, 
however,  render  it  unsuitable  for  these  uses,  particularly  for  the  latter. 

Cotton  Seed  Oil. 

Several  oils  have  claims  to  be  ranked  next  in  importance  to  linseed  oil.  One  of 
these  is  cotton  seed  oil,  as  obtained  from  the  seeds  of  the  cotton  plant.  There  are 
several  varieties  of  cotton  plant,  such  as  the  Upland  and  Sea  Island  varieties,  as  grown 
in  the  United  States,  and  the  Egyptian,  Indian,  Brazilian,  and  Peruvian.  The  fruit 
or  "  boll  "  of  the  plant,  when  ripe,  bur.sts  opeii  and  exposes  the  cotton  in  the  form  of 
a  fluffy  mass.  In  this  condition  it  is  gathered  and  is  Itnown  as  seed  cotton,,  for  it 
consists  of  about  one-third  by  weight  of  fibre  and  two-thirds  of  seed.  The  fibre  is 
attached  to  the  seeds  and  has  to  be  separated  therefrom  in  a  cotton  gm.  The  degree 
of  success  attending  the  ginning  is  an  important  consideration  in  the  subsequent 
recovery  of  the  oil  from  the  seeds.  The  Egyptian  plant  yields  a  black  seed,  from  which 
the  fibre  is  easily  removed  completely  in  the  gin.  The  American  and  Indian  seeds, 
on  the  other  hand,  are  white  and  leave  the  gin  with  a  considerable  amount  of  the  fibre 
still  adhering  to  their  husks.  Such  seeds  are  sometimes  reginned  in  the  mill  before 
being  further  treated.  Practice  differs,  however.  In  some  cases  the  seeds  are  crushed 
as  received,  the  fibres  and  husks  being  allowed  to  pass  into  the  cake.  In  other  cases, 
as,  for  example,  very  frequently  in  the  case  of  American  "  Upland  "  seed,  the  fibre 
is  removed,  the  husks  are  taken  off  in  a  decorticating  machine,  and  the  kernels,  or 
"  meats  "  as  they  are  called,  are  alone  crushed.  The  seeds  on  the  average  consist  of 
60  per  cent,  keiuiel  and  40  per  cent.  husk.  The  amoimt  of  oil  which  they  contam  varies 
from  18  to  24  per  cent.,  according  to  the  country  and  plant  producing  them. 

Cotton  seed  kernels,  the  real  source  of  the  oil,  contain  a  strong  deep-brown 
colouring  matter.  Owing  to  the  difficulty  of  refining  the  crude  oil,  the  seed  not  required 
for  planting  was,  mitil  a  little  over  sixty  years  ago,  thrown  away,  although  as  long  ago 
as  1783  the  Royal  Society  of  Arts  endeavoured  to  encourage  the  production  of  cotton 
seed  oil  and  cotton  seed  cake.  In  America,  up  to  1860,  the  disposal  of  the  seed  fi'om 
the  ginning  plant  was,  in  fact,  a  problem  of  no  little  concern  to  the  proprietor.  He 
was  heavily  penalised  if  he  allowed  the  seed  to  accumulate  near  the  gin,  and  was 
strictly  forbidden  to  get  rid  of  it  by  throwing  it  into  any  river  or  stream.  The  waste 
seed  was  to  a  small  extent  used  as  a  maniu'e,  but  the  bulk  of  it  had  to  be  bunied. 
Later  on  it  was  discovered  that  the  residue  left  after  millmg  the  seed  for  its  oil  retained 
all  the  fertilismg  properties.  Cotton  seed  meal,  that  is,  the  press  cake  ground  up,  is 
still  largely  used  as  a  manure  for  sugar  cane,  cotton,  com,  tobacco,  and  so  on.  It  is 
now,  howev^er,  realised  that  the  most  economical  mamier  of  using  it  is  to  feed  it  to 
cattle  and  to  use  the  resulting  manure,  which  retains  80  to  90  per  cent,  of  the  original 
fertilising  value,  on  the  ground. 

Cotton  .seed  oil  is  a  so-called  .semi-drying  oil.  It  absorbs  oxygen  slowly  under 
ordinary  conditions,  but  by  blowing  air  through  it  at  about  100"  C.  the  absorption  can  be 
increased.  Blown  cotton  seed  oil  and  other  semi-drying  oils  similarly  treated  become 
thickened  and  appear  in  den.sity  and  viscosity  like  castor  oil.  They  are  produced  on 
a  considerable  scale  and  when  dissolved  in  light  mineral  oils  are  used  as  lubricants. 
Refined  cotton  seed  oil  is  in  extensive  use  for  edible  purposes.  It  appears  on  the  table 
as  salad  oil,  it  is  used  by  the  sardme  tinning  industry,  and  under  the  name  of  butter 
oil  it  fonns  one  of  the  chief  raw  materials  of  the  margarine  manufacturer  and  of  the 
manufacturer  of  lard  substitute,  or  compound  lard  as  it  is  called.  Apart,  from  the  very 
great  use  of  cotton  seed  oil  for  edible  purposes  its  chief  industrial  emplojTuent  is  in 
the  soap-making  industry.     It  is  frequently  "used  in  this  connection  by  itself.     As  an 


8  THE   PRODUCTION   AND   TREATMENT   OF   \'EGETABLE   OILS 

ingredient  of  toilet  soap  it  is  commonly  mixed  \rith  tallow  or  cocoa-nut  oil.     It  is  also 
widely  used  in  the  manufacture  of  soap  powder. 

Olive  Oil. 

Olive  oil  is  in  several  respects  chemically  and  industriaUy  closely  similar  to  cotton 
seed  oil.  The  latter  being  cheaper  :s  frequently  substituted  for  it.  notably  for  edible 
purposes.  The  reputation  of  oUve  oil  as  an  edible  oil  is.  however,  too  great  for  it  ever 
to  be  supplanted  completely  by  any  other.  The  olive  tree  is  chiefly  cultivated  in  the 
countries  bordering  the  Mediterranean.  Recently  attempts,  not  always  ^^-ith  success, 
have  been  made  to  grow  it  in  India,  California.  South  Africa,  and  Australia.  The 
fruit  of  the  oUve  consists  of  rind,  flesh,  stone,  and  seed  kernel.  All  parts  contaui  oil. 
The  fleshy  part,  forming  80  per  cent,  of  the  whole,  contains  from  40  to  fiO  per  cent,  of 
oil  and  yields  the  best  oil  for  edible  purposes.  To  produce  tliis  oil  the  fruit  is  gathered 
before  it  is  quite  ripe  and  is  peeled  and  stoned.  The  flesh  is  then  pressed  by  itself. 
The  kernels  are  crushed  separately  and  yield  an  inferior  '  olive  kernel  oil."  The  pulp 
left  after  the  pressing  of  the  flesh  may  contain  as  much  as  20  per  cent,  of  oil.  It  is 
gromid  up  with  hot  water  and  allowed  to  stand  nntil  the  broken  up  cellular  tissue 
rises  to  the  surface.  This  is  again  pressed  for  a  second  quahty  oil.  The  residue  is 
finally  extracted  with  solvents,  commonly  carbon  disulphide.  Such  extracted  oil 
acquires  a  deep-green  colour  from  the  chlorophyll  in  the  fruit,  and  is  principally  used 
for  soap-maldng.  In  some  mills  the  original  fruit  is  not  stoned  before  being  pressed 
for  the  first  time,  but  is  crushed  as  a  whole.  The  oil  yielded  is  of  a  less  perfect  quality 
than  that  obtained  by  the  other  process,  for  it  contains  the  poorer  oil  derived  from  the 
kerne's. 

The  oil  derived  from  the  fir.st  pressing  of  the  fruit  is  almost  invariably  used  for 
edible  purposes.  A  second  or  third  pressing  is  commonly  adopted.  The  oil  so  obtained 
is  used  for  soap-making  and  for  lubricating  and  burning  purposes,  for  olive  oil  is  a 
non-drj-ing  oil.  The  press  cake  is  sometimes  used  locally  as  a  cattle  food.  The  value 
of  the  oil.  however,  makes  it  pay  to  carry  the  recoven,-  to  the  greatest  pos.«ib!e  extent. 
Hence  the  last  drop  of  oil  is  usually  recovered  by  the  chemical  solvent  process  and  the 
residue  sold  as  manure. 

Castor  Oil. 

The  castor  tree  or  shrub — it  is  found  in  both  forms — grows  in  all  tropical  and 
sub-tropical  countries.  The  seeds  are  enclosed  withm  a  rough  outer  shell  or  pod. 
and  themselves  consist  of  a  husk  containing  a  white  soft  kernel.  The  kernel  forms 
80  per  cent,  of  the  seed  and  j-ields  from  46  to  53  per  cent,  of  its  weight  in  oil.  The 
husks  are  oil-less.  The  bulk  of  the  seed  u.«ed  in  commerce  comes  from  the  East 
Indies. 

Ca«;tor  oU  is  of  the  non-drying  class  and  is  of  great  value  as  a  lubricant.  It  is 
extensively  used  in  the  soap  industr\-.  Treated  with  concentrated  sulphuric  acid  it 
yields  a  fatty  substance  knowii  as  Turkey  Red  oil.  which  is  used  in  preparing  cotton 
fibre  for  dyeing  in  the  Turkey  Red  industry-.  Its  medicinal  use  depends  upon  the 
fact  that  it  contains  an  alkaloid.  This  alkaloid  in  excess  is  poisonous,  and  as  it  is 
retained  in  considerable  quantity  in  the  residue  left  after  crushing  the  seeds,  castor 
oil  cake  is  unfit  for  a  cattle  food.  Consequently  it  is  extracted  with  solvents  to  recover 
a  quality  of  oil  suitable  for  soap-making  and  other  technical  pirrposes.  The  ultimate 
residue  is  used  as  a  manure. 

Castor  seeds  are  commonly  pressed  cold  to  obtain  medicinal  oil  and  then  pressed 
a  second  or  third  time  in  a  hot  condition  to  obtain  technical  quality  oils.     The  seeds 


THE    PRINCIPAL   VEGETABLE    OILS  9 

are  frequently   crushed  with  their  husks  on,   but   sometimes  they   are   previously 
decorticated  and  their  kernels  alone  placed  in  the  press. 

Palm,  Palm  Kernel,  and  Cocoa-nut  Oils. 

The  fruit  of  the  African  oil  palm  consists  of  a  fleshy  outer  layer  or  pericarp 
surrounding  a  hard  woody  shell  within  which  is  the  seed  kernel.  Roughly,  the  shell 
forms  50  per  cent,  of  the  whole,  the  fleshy  pericarp  35  per  cent.,  and  the  kernel  15  per 
cent.  Of  the  pericarp  50  per  cent,  or  so  is  oil,  while  the  kernel  yields  about  45  per 
cent.  In  the  case  of  the  olive  the  oils  recovered  from  the  fleshy  part  and  from  the 
kernels  are  practically  the  same.  In  the  case  of  the  palm  tree  fruit  they  are  quite 
different.  Palm  oil,  the  product  derived  from  the  pericarp,  is  used  principally  in  the 
making  of  soap  and  candles.  The  pericarp,  owing  to  its  nature,  has  to  be  worked  up 
as  soon  as  the  fruit  is  pulled.  Consequently,  the  factory  is  erected  near  the  plantation. 
The  kernels,  separated  from  the  pericarp,  are  shipped  to  the  United  Kingdom,  Ham- 
burg, etc.,  and  are  treated  by  cru.shing  and  extraction  with  solvents  for  the  recovery 
of  palm  kernel  oil.  This  oil  in  a  fresh  condition  is  largely  used  in  the  manufacture 
of  margarine,  and  to  a  considerable  extent,  when  suitably  treated,  in  the  manufacture 
of  chocolate.  The  poorer  qualities  and  the  extracted  oil  are  suitable  for  soap,  candle 
and  paint  making.  Palm  kernel  oil  cake  is  somewhat  deficient  in  nitrogen,  so  that  its 
value  as  a  cattle  food  is  less  than  that  of  some  other  qualities  of  cake.  This  deficiency 
also  renders  the  residue  from  the  extraction  process  of  low  value  as  a  manure. 

Cocoa-nuts  are  obtained  from  a  tree  of  the  palm  family,  not,  of  course,  from  the 
cocoa  tree.  The  fleshy  layer  inside  the  nut,  when  dried  either  in  the  sun  or  by  artificial 
heat,  is  kno^vn  as  "  copra."  The  undried  flesh  contains  about  half  its  weight  of  water, 
so  that  by  drying  it,  an  operation  carried  on  at  the  place  where  the  nuts  are  gathered, 
a  considerable  saving  of  freight  is  affected.  The  copra,  shipped  to  the  oil  mills,  is 
shredded  and  crushed  hot.  It  yields  roimd  about  64  per  cent,  of  its  weight  in  oil, 
but  this  figure  is  subject  to  variation  according  to  the  precise  method  adopted  for 
drying  the  copra  by  the  gatherers.  Cocoa-nut  oil  is  very  closely  similar  to  palm 
kernel  oil  and  is  used  for  much  the  same  purposes,  that  is  to  say,  chiefly  in  the  making 
of  margarine  and  of  soap. 

These  three  oils,  palm,  palm  kernel,  and  cocoa-nut  oils,  are  all  of  the  non-drying 
type,  and  at  ordinary  European  temperatures  are  to  be  regarded  as  vegetable  fats 
rather  than  as  oils. 

It  may  be  noted  here  that  although  cocoa-nuts  do  not  grow  on  cocoa  trees,  still 
cocoa-nut  oil — and  also  pahn  kernel  oil — is  of  great  value  to  the  chocolate  manufacturer. 
The  cocoa  bean  when  roasted  and  ground  contains  about  50  per  cent,  of  fat,  or  "  cocoa 
butter  "  as  it  is  called.  This  fat  lenders  the  cocoa  powder  difficult  of  mixture  with 
boiling  water  and  indige.'ftible.  It  i.s  besides  a  valuable  .substance  in  itself,  being  used 
in  medicine  and  soap-making.  Hence  it  is  frequently  removed  to  the  extent  of  about 
half  its  original  amount  by  submitting  the  ground  cocoa  powder  to  hydraulic  pressure. 
In  working  up  the  cocoa  powder  into  chocolate  of  the  best  quality  a  portion  of  the 
abstracted  cocoa  butter  is  returned  to  it.  In  other  chocolates  the  valuable  cocoa 
butter  is  omitted,  and  cocoa-nut  oil,  suitably  treated,  or  palm  kernel  oil  is  used  instead. 

Soya  Bean  Oil. 

The  soya  bean  flourishes  in  Manchuria,  China,  and  Japan.     Li  Manchuria  the 

cultivation  of  the  plant  is  .stated  to  have  been  the  main  agricultural  industry  for 

centuries,  while  the  production  of  soya  bean  oil  and  .soya  bean  cake  formed  the  most 

important  manufactures  of  the  country.    The  bean  cakes  have  for  long  formed  one 


10        THE   PRODUOTIOX   AXD   TREATMEXT   OF   \T:GETABLE   OILS 

of  the  chief  articles  of  food  for  the  inhabitants.  Nevertheless,  the  bean  and  the  oil  it 
yields  were  almost  unlciio\\ii  in  Eiuope  until  the  Russo-Japanese  Wav.  Since  then  the 
production  and  use  of  soj  a  bean  oil  and  soya  bean  cake  have  developed  phenomenally. 
The  oil  in  Europe  now  rivals  that  obtained  from  the  cotton  seed,  while  the  cake,  on 
the  Continent  at  least,  is  contesting  the  position  as  a  food  for  milch  cows  held  by 
linseed  and  cotton  seed  cake.  The  oil  belongs  to  the  semi-diying  class,  and  is  used 
for  edible  purposes,  as  an  illuminant,  in  soap-making,  and  in  the  manufacture  of 
linoleum.  The  bean  contains  about  18  per  cent,  of  oil,  and  in  the  press  yields  from 
10  to  13  per  cent. 

Rape  or  Colza  Oil. 

The  rape  plant  is  gi'OMii  extensively  in  many  European  countries,  notably  in 
Russia.  It  is  cultivated  in  British  India  to  an  extent  which  renders  the  annual  crop 
second  onh'  in  importance  to  the  linseed  crop.  The  bullv  of  the  Indian  seed  is  shipped 
to  England,  but  C4ermany  used  to  have  a  preponderating  hold  on  other  sources  of 
supply.  Rape  oil  belongs  to  the  semi-drjang  class,  and  is  principally  used  for  burning 
purposes  and  as  a  lubricant.  In  the  latter  case  the  oil  is  frequently  '"  blowTi,"  as 
mentioned  above  under  cotton  seed  oil.  To  a  small  extent  rape  oil  when  obtained  by 
"  cold  drawing  "  is  used  for  edible  purposes,  notably  by  bakers  in  the  production  of 
bread.  It  is  commonly  employed  as  a  quenching  medium  for  steel  plates,  etc.,  and 
on  the  Continent  is  used  occasionally  in  the  manufacture  of  soft  soap.  The  seed 
contains  anything  from  33  to  43  per  cent,  of  oil.  It  is  frequently  extracted  by  means 
of  solvents.  The  oil  apparently  contains  a  poisonous  element.  Consequently  rape 
seed  cake  is  not  greatly  valued  as  a  cattle  food.  It  may,  in  fact,  be  said  that  the  bulk 
of  the  residue  left  after  either  crushing  or  extraction  M'ith  solvents  is  used  as  a  manure. 

Mustard  Oil. 
Tliis  oil  is  obtained  from  the  black,  white,  or  wild  mustard  plant,  and  is  used  in 
soap-maliing  and  as  a  substitute  for  or   adulterant  in  rape  oil,  to  which  it  is  closely 
similar.     The  cake  left  after  crushing  is,  however,  a  more  important  product  than  the 
oil.     When  ground  this  cake  gives  the  mustard  of  the  domestic  table. 

ScjNFLowER  Oil. 
The  sunflower  is  cultivated  for  the  sake  of  its  seeds  on  an  immense  scale  in  Russia, 
Italy,  India,  and  China.  The  seeds,  raw  or  roasted,  are  used  in  Russia  as  an  article 
of  diet.  The  oil  recovered  from  them  by  crushing  is,  when  refined,  considered  by 
some  to  equal  olive  oil  for  edible  purposes.  Its  chief  use,  however,  is  in  soap  and 
candle-making.  The  seeds  contain  from  20  to  23  per  cent,  of  oil.  For  cattle-feeding 
purposes  the  cake  is  not  only  veiy  palatable,  but  being  rich  in  nitrogenous  matter  is 
of  great  food  value.  Sunflower  oil  belongs  to  the  drs'ing  class.  The  sunflower  is  verj- 
readily  cultivated,  and  produces  a  high  yield  of  seeds.  It  is  believed  that  the  Central 
Empires,  cut  off  as  they  are  at  present  from  many  important  sources  of  oils  and  fats, 
are  cultivating  the  sunflower  on  an  exten.sive  scale  in  an  attempt  to  reduce  the  deficiency. 
They  are  probably  growing  flax — for  linseed  oil — also  on  a  considerable  scale  ;  but 
flax,  it  is  to  be  noted,  rapidly  exhausts  the  soil  and  is  therefore  in  all  hkehhood  bemg 
cultivated  to  an  extent  only  slightly  greater  than  in  peace  time.  It  maj'  perhaps  be 
added  that  the  rumours  recently  in  circulation  as  to  Germany's  shortage  of  glycerine 
and  the  horrible  means  she  is  adopting  to  make  it  good  cannot  be  accepted  as  true  by 
those  qualified  to  judge.  In  the  first  place  Germany  uses  little  or  no  glycerme  in  the 
production  of  her  explosives,  differing  in  tlus  respect  from  this  country,  which,  of 


THE    PRINCIPAL    VEGETABLE    OILS  11 

course,  dt-pends  extensively  upon  nitro-glycerine.  In  the  second  place  the  yield  of 
glycerine  from  the  source  suggested  would  be  altogether  too  insignificant  to  justify 
the  cost,  trouble,  and  difficulty  of  recovering  it.* 

Poppy  Seed  Oil. 
The  seed  of  the  poppy  contains  from  45  to  50  per  cent,  of  an  oil  which,  when 
'■  cold  dra^^^l,"  is  almost  colourless,  has  little  odour,  and  possesses  a  pleasant  taste. 
It  is  in  extensive  use  on  the  table  as  a  salad  oil,  and  is  highly  valued  by  arti.sts  and 
artists'  colourmen.  The  seeds  are  usually  expressed  twice,  the  second  pressing  being 
carried  out  hot  and  yielding  an  inferior  oil  which  is  extensively  employed  in  making 
paints  and  soft  soaps.  The  oil  belongs  to  the  drying  class.  Poppy  seed  cake  is  rich 
in  nitrogen  and  is  highly  valued  as  a  cattle  food. 

*  Since  these  remarks  were  written,  the  rumours  referred  to  have  become  a  popular  article 
of  belief,  iu  this  country  at  least,  and  have  received  what  would  appear  to  be  semi-official 
confirmation. 


CHAPTER    III 
PREPARATORY  .ALICHINERY   FOR   COPRA   AND   LINSEED 

From  the  engineering  point  of  view  the  machinery  and  plant  used  in  the  production 
of  vegetable  oils  may  conveniently  be  divided  into  four  classes.  First  we  have  what 
may  be  called  the  preparatory  machinery,  the  plant,  that  is  to  say,  which  deals  with 
the  seeds,  nuts  or  fruit  as  received  from  the  growers,  and  reduces  them  to  a  form 
suitable  for  treatment  m  the  subsequent  oil  recoverj^  processes.  Xext  we  have  the 
presses  wherein  the  material  so  prepared  is  crushed.  Thirdly,  there  is  the  plant 
emplo}"ed  when  the  oil  is  extracted  by  chemical  solvents,  either  as  an  alternative  to 
crushing  or  as  supplementan,-  thereto.  Fourthly,  there  is  the  plant  employed  to 
refine  the  oil.  To  these  four  classes  of  oil  mill  machinen,'  and  plant  a  fifth  has  to  be 
added.  This  is  not  so  much  concerned  with  the  production  of  the  oil  as  with  the 
production  and  treatment  of  the  cake. 

Of  the  machinery'  m  the  preparatorj-  class  it  may  be  said  that  there  are  three 
distinct  divisions.  In  the  first  of  these  we  have  the  machines  and  appliances  used  in 
the  separation  of  the  oil-bearing  portion  of  the  natural  product  from  the  non-oil  beai-ing 
portions,  or  from  secondary  oil-bearing  portions  whicli  it  is  desired  to  treat  apart  from 
the  fii-st.  The  portions  thus  separated  have  in  general  to  be  prepared  for  the  presses 
b}' j'rushing,  shreddmg,  and  otherwise  reducing  them  to  a  meal  of  sufficient  fineness 
to  present  the  mmute  oil  vesicles  in  the  best  form  to  the  action  of  the  press.  The 
machines  thus  employed  form  the  second  of  our  three  divisions.  The  third  division 
embraces  machines  and  apphances  concerned  with  the  manipulation  of  the  meal  just 
before  it  goes  into  the  press.  These  manipulations  include  the  heatmg  of  the  meal 
to  a  suitable  temperature  and  its  rough  moulding  into  slabs  or  cakes  for  insertion 
within  the  press.  It  will  be  imderstood,  of  cour,se,  that  this  is  a  general  outHne  only, 
and  that  all  oil-bearing  vegetable  products  do  not  necessarily  require  the  whole  run 
of  the  appliances  thus  indicated.  Thus  linseed,  rape  seed,  and  similar  small  seeds 
do  not  entail  the  use  of  any  preparatory  machines  of  the  first  division.  On  the  other 
hand,  cotton  seed  frequent!}-,  and  palm  kernels  nearly  always,  require  the  use  of 
machines  of  all  three  kinds.  The  machines  of  the  first  division  are  in  general  of  a 
speciahsed  nature,  that  is  to  say,  they  are  in  most  cases  each  designed  to  deal  with  one 
particular  class  of  seed.  The  machines  of  the  second  division  are  very  similar  among 
themselves  whatever  the  seed  or  nut  being  treated.  The  machines  of  the  third  division 
do  not  varj'  with  the  nature  of  the  seed  being  dealt  with,  for  by  the  time  the  seed 
reaches  them  it  has  lost  all  its  outsta-.ding  original  physical  features,  and  whatever 
it  was  to  begin  with  is  now  in  the  form  of  more  or  less  fine  meal. 

We  now  pass  to  a  description  of  the  more  oi  less  specialised  preparatory  machinery 
in  use  or  designed  for  the  treatment  of  certain  important  oil-bearing  substances. 
Before  domg  so  we  desire  to  make  two  general  remarks  which  may  avoid  occasion  for 
misunder-standing.  In  the  first  place  certain  of  the  machines  described  below  are 
suitable  for  treating  substances  other  than  that  mentioned  in  the  heading  under  which 
they  appear.  Secondly,  the  fact  that  any  given  machine  is  mentioned  as  being  made 
by  such  and  such  a  firm  does  not  necessarily  mean  that  it  is  made  onlj-  by  that  finn. 


INSERT  FOLDOUT  HERE 


PREPARATORY   MACHINERY   FOR   COPRA    AND    LINSEED  13 

Preparatory  Machtneby  for  Copra. 

Tlie  cocoa-nuts  as  gathered  have  first  to  be  split  open.  The  split  nuts  are  then 
set  in  the  siui,  placed  in  a  kiln,  often  of  rude  construction,  or,  as  is  now  becommg  the 
practice,  deposited  in  a  lightly  built  galvanised  iron  house  beneath  the  floor  of  which 
steam-heating  pipes  are  disposed.  In  either  of  these  ways  the  moisture  contained 
in  the  flesh  of  the  nut,  amounting  to  about  half  the  original  weight  of  the  flesh,  is 
driven  off  and  the  flesh  itself  becomes  loosened  from  the  shell.  The  dried  flesh — copra 
— is  then  exported.  Great  care  is  necessary  in  carrying  out  the  drying  process,  for 
the  material  can  readily  be  spoilt  by  attempting  to  drive  off  the  moisture  too  rapidly, 
with  the  result  that  the  flesh  is  discoloured  and  the  oil  recovered  from  it  is  difficult  to 
refine.  On  the  other  hand,  the  natural  moisture  in  the  flesh  must  not  be  allowed  to 
remain  unduly  long  in  contact  with  the  oil  in  the  flesh  after  the  nuts  have  been  split. 
If  this  is  permitted  the  water  will  hydrolise  the  oil,  that  is  to  say,  it  will  enter  into 
chemical  combmation  with  it  and  split  it  up  into  two  elements,  namely,  glycerine  and 
free  fatty  acid. 

The  splitting  of  the  nuts  was,  and  still  is,  frequently  performed  simply  with  a 
hammer.  More  scientific  means  are  now,  however,  being  introduced.  In  Fig.  1  we 
give  the  general  ari'angement  of  a  machine  for  the  purpose  made  by  Rose,  Downs  &, 
Thompson,  Ltd.,  of  Hull.  This  machine  deals  with  nuts  as  gathered,  that  is  to  say, 
it  treats  them  with  their  outer  husks  still  on.  By  means  of  three  circular  l^nives 
having  saw-like  teeth,  and  spaced  at  120  degrees  apart,  it  cuts  through  husk,  shell,  and 
kernel,  and  divides  the  whole  into  three  parts.  The  knives  are  momited  on  three 
shafts  forming  a  triangle  in  plan,  and  geared  together  by  bevel  wheels.  One  of  the 
Icnife  shafts  is  driven  by  spur  wheel  and  pinion  from  a  belt-driven  comitershaft 
canying  a  flywheel.  The  knives  are  1  ft.  5  in.  in  diameter  and  run  at  about  25  revo- 
lutions per  minute.  A  more  or  less  conical  sheet  metal  hopper  is  fixed  over  the  knives. 
The  loiives  pass  through  openings  in  the  sides  of  this  hopper.  Three  bent  plates  or 
knees  are  attached  to  the  inside  of  the  hopper  to  act  as  guides  for  the  nuts  and  lead 
them  to  the  centre  of  the  hopper.  There  they  are  caught  by  the  Iviiives  and  are  cut 
and  carried  do\viiwards  to  fall  on  to  the  base  plate  of  the  machme.  About  2  h.p.  is 
required  to  drive  this  machine.  Its  output  may  be  returned  at  2,000  nuts  per  hour. 
It  will,  in  fact,  split  the  nuts  as  fast  as  one  man  can  feed  them  to  it. 

The  copra  as  received  at  the  oil  mill  in  this  or  some  other  coiuitry  is  in  the  form 
of  lumps  of  considerable  size.  These  have  to  be  reduced  to  the  form  of  "  meal  "  by 
various  shreddings  and  gi'indings.  Before  doing  so,  however,  it  is  necessary  closely 
to  examine  the  material,  for  it  is  frequently  found  to  contain  an  odd  assortment  of 
scrap  iron,  such  as  hammer  heads,  bolts,  nuts,  horseshoes,  nai!s,  etc.  The  native  and 
other  gatherers  of  palm  nuts,  copra,  and  so  on,  are  paid  by  weight,  and  on  occasion 
do  not  scruple  to  turn  a  dishonest  penny.  Many  breakdowns  of  machinery  have 
been  caused  by  the  undetected  presence  of  sucji  foreign  matter  in  tlie  material  treated, 
particularly  so  in  the  case  of  mills  handling  copra  and  other  sub.stances  which  as  part 
of  the  preparatory  process  have  to  be  gi'ound.  To  remove  the  objectionable  substances 
resort  is  commonly  made  to  hand  picking  the  material  before  anything  else  is  done  to 
it.  This  process  is  slow  and  monotonous,  so  that  it  is  not  sui-prising  that  modern 
practice  should  call  for  some  mechanical  means  of  perfomiing  the  operation. 

An  appliance  of  this  nature,  a  magnetic  separator,  made  by  Rose,  Dowtis  & 
Thompson,  Ltd.,  is  illustrated  in  Fig.  2.  The  material  to  be  treated  is  delivered  on 
to  a  sloping  sheet  metal  tray  supported  on  four  flexible  spring  rods  A  and  rapidly 
vibrated  by  means  of  a  connecting  rod  B,  and  short-throw  crankshaft  C.      The  shaking 


14 


THE   PRODUCTIOX   AXP   TREATMENT   OF  A'EGETABT.E   OILS 


action  of  tliis  tray  distributes  the  material  luiifomily.  and  further  causes  the  heavy 
iron  ingi-edients  to  sink  by  gi-a-vity  to  the  bottom  of  the  batch.     Sometimes  the  tray 


T~E    Ekcineeb"  S.«i>.    Sc 

Fig.  2. — Magnetic  Separator  for  Copra,  etc. — Rose,  Iiowns  &  Thompson. 

can  be  made  in  the  form  of  a  screen,  when  it    will  serve  the  additional  purpose  of 
separating  any  fine  impurities,  sand,  chips,  and  so  on.  from  the  oil-bearing  substance. 


HBS-^^ 

K      ***1   1                1  L  C  r''^-^!!IB 

^j^^lJUgj^^^m^^^^^ 

Fig.  .J. — rreliminary  Breaking  Machine — Manlove,  Alliott. 

The  material  leavuig  the  tray  falls  on  to  a  power-driven  magnetic  barrel  D,  provided 
with  several  rows  of  studs,  each  row  being  momited  on  a  separate  commutator  section 
of  the  barrel.     The  non -magnetic  material  is  carried  round  the  barrel  and  drops  off 


PREPARATORY    IMACHTNERY    FOR    COPRA    AND    LINSEED 


15 


at  the  front  into  a  suitable  hopper.  The  iron  intruders  are  carried  round  to  tlie  back 
luitil  they  reach  a  point  at  which  the  section  of  the  barrel  to  which  thej'  are  adhering 
is  automatically  demagnetised  for  a  moment  to  permit  them  to  drop  off.  The  size 
of  machine  illustrated  has  an  output  of  from  1  to  1 J  tons  per  hour.  It  is  driven  from 
the  small  pulley  at  the  end  of  the  shaker  crankshaft,  which  shaft  is  rotated  at  300  revo- 
lutions per  minute.  About  a  liorse-power  is  absorbed  in  driving  the  machine.  The 
current  required  for  the  magnetic  barrel  is  7  amperes  at  40  volts,  and  can  be  conve- 
niently supplied  by  a  snaall  belt-driven  dynamo  provided  for  the  purpose. 

JMachines  for  Reducing  Copra,  etc. 

The  reduction  of  copra  as  imported  to  the  form  of  meal  for  the  press  requiies 

special  consideration.     The  copra  is  generally  received  in  pieces  of  such  a  size  that  it 

has  to  be  reduced  in  three,  four,  or  even  five  separate  .stages.     Usually  these  reductions 

are  effected  by  means  of  rolls.     For  the  first  reduction,  however,  rolls  may  be  dispensed 


Fig.  4.— Shredding  and  Crushing  KoUs  for  Copra,  etc.- -A.  F.  Craig. 

with  and  a  preliminary  breaking  machine,  Fig.  3,  as  made  by  Manlove,  Alliott  &  Co., 
Ltd.,  of  Nottmgham,  u.sed  m  their  place.  This  machine  is  claimed  to  be  considerably 
cheaper  than  rolls  both  in  first  cost  and  in  maintenance,  and  to  rmi  without  attention 
so  long  as  it  is  fed  evenly.  The  casing  of  the  machine  is  a  cast-iron  barrel  ribbed 
internally  to  prevent  the  copra  rotating  as  a  ma.ss  within  it.  The  casing  contains 
a  power-driven  segmental  worm  having  a  coarse  pitch  at  tlie  feed  end  and  a  finer 


16 


THE  PRODUCTION  AND  TREATJfENT   OF  \TEaETABLE   OILS 


pitch  at  the  dehvery  end.  At  the  latter  end  there  is  fitted  a  hardened  perforated  steel 
plate  through  which  the  partially  broken  copra  is  forced  bj^  the  worm.  A  four-bladed 
knife  revolves  agauast  the  worm  side  of  this  plate  anc^cuts  the  copra  as  it  passes  through 
the  perforations  besides  assisting  its  passage  through  these  holes.  The  worm  shaft 
is  fitted  with  Hoffmann  ball  thrust  bearmgs.  The  perforated  plate  can  be  readily 
changed  and  one  with  smaller  holes  .substituted  for  it.  This  change  pennits  of  the 
machine  being  used  with  e:[ual  facility  for  the  breaking  of  palm  kernels. 

The  material  as  thus  disintegrated  is  next  reduced  a  step  further  by  means  of 
rolls  which  shred  and  ciush  it.  A  set  of  rolls  suitable  for  this  purpose,  as  made  by 
A.  F.  Craig  &  Co.,  Ltd.,  of  Paisley,  is  illustrated  in  Figs.  4  and  5.  The  example 
here  represented  has  two  pairs  of  rolls,  the  upper  pair  of  which  is  fluted  longitudinally, 
the  lower  pair  being  plain.     The  rolls,  as  is  usual,  are  of  chilled  cast  iron  and  are 


The    Engineer" 


Fig.  5. — Shredding  and  Ciushing  Rolls — Craig 


hydraulicallj'^  pressed  on  to  steel  shafts.  One  roll  in  each  pair  runs  in  fixed  bearings, 
the  other  running  in  sliding  bearings  which  are  acted  upon  by  relief  springs  disposed 
within  cii-cular  boxes  on  the  frame  sides.  The  force  of  these  springs  is  adjustable  to 
give  the  required  degree  of  pressm'e  between  the  I'olls.  In  a  common  size  of  machine, 
one  capable  of  dealing  with  15  cwt.  of  material  per  hour,  the  rolls  ai'e  48  in.  long.  The 
lower  rolls  are  each  14  in.  in  diameter,  and  run  at  about  130  revolutions  per  minute. 
The  upper  rolls  are  of  different  diameters  and  rotate  at  different  speeds.  The  larger 
roll  is  16  in.  in  diameter,  and  rims  at  about  110  revolutions  per  minute,  the  smaller 
roll  being  12  in.,  and  ruiming  at  about  47  revolutions.  The  peripheral  speed  of  the 
larger  roll  is  thus  about  three  times  that  of  the  smaller.  As  a  result,  the  partially 
reduced  material  falling  from  the  hopper  between  the  top  rolls  is  shredded  by  the 
fluted  surfaces.  Falling  between  the  plam  lower  rolls  it  is  still  farther  reduced  by  a 
crushmg  action.  Each  of  the  four  rolls  is  provided  with  a  scraper  worldng  against 
its  lower  portion.  The  feed  hopper  consists  of  a  tiough  formed  over  the  smaller  of 
the  two  top  rolls.  At  the  front  a  fixed  plate  extends  from  it  to  the  surface  of  the  roll. 
At  the  back  a  hinged  plate,  adjustable  by  means  of  one  or  two  screws  and  hand  wheels, 
permits  the  quantity  of  material  passijig  out  of  the  hopper  to  be  regulated.  About 
15  b.li.p.  is  consumed  in  driving  a  set  of  rolls  of  the  size  mentioned  in  this 
paragi'aph. 


PREPARATORY    MACHINERY    FOR    COPRA    AND    LINSEED 


17 


A  set  of  rolls  made  by  Manlove,  Alliott  &  Co.,  Ltd.,  for  the  same  purpose  aa  the 
above  is  represented  m  Fig.  6.  Li  this  case  there  are  three  pairs  of  chilled  cast-iron 
rolls.  All  six  are  of  the  same  size,  each  being  15  in.  in  diameter  and  36  in.  long  The 
two  top  pairs  are  spirally  fluted  and  are  driven  from  the  belt  pulley  at  the  right-hand 
end  of  the  machine  through  double  helical  gearhig.     The  two  lolls  in  each  of  these 


Flo.  6. — Rolls  for  further  Reduction  of  Copra — Manlove,  Alliott. 

upper  pairs  rotate  at  different  speeds  so  that  the  action  is  a  shredding  and  grinduig 
one.  The  two  lower  rolls  are  plain  and  are  separately  driven  at  equal  speeds  by  the 
belt  pulley  at  the  left-hand  end  of  the  machine.  The  material  at  this  point  is  rolled 
rather  than  ground.  As  before,  the  rolls  are  fitted  with  scrapers.  The  feed  hopper 
is  provided  with  an  adjustable  shutter  and  a  power-driven  feed  roll  which  ensures  the 
material  being  delivered  evenly  along  the  length  of  the  rolls,  an  important  item  in 
successful  working.  These  rolls  are  made  in  various  sizes  to  treat  from  12  to  20  cwt. 
of  material  per  hour,  and  in  their  driving  consume  from  8  to  10  b.h.p. 


18        THE   PRODUCTION   AND  TREATMENT   OF   VEGETABLE   OILS 

The  final  reduction  of  the  material  to  meal  of  the  proper  degree  of  fuieness  is 
carried  out  in  powerful  rolls,  of  which  an  example  made  by  Messrs.  Manlove,  Alliott  is 
illustrated  in  Fig.  7.  The  action  required  is  one  of  rollmg  not  of  giindmg.  The  five 
rolls  in  the  machine  illustrated  are  stacked  vertically,  and  are  driven  positively  by 
means  of  a  double  helical  gear-wheel  at  each  end  of  each  roll.  The  rolls  rotate  at 
equal  speeds  and  are  either  plain  or  lightly  fluted,  both  styles  being  often  found  in  the 
same  macliine  at  once.  The  material  leaving  the  hopper  at  the  top  is  guided  in  a 
sinuous  course  through  the  rolls  by  means  of  four  inclmed  plates  let  into  the  machme 
framework  on  alternate  sides  of  the  rolls.     The  lowest  roll  spindle  carries  two  fast  and 


Fig.  7. — Final  Seduction  Rolls — Manlove,  Alliott. 

1  wo  loose  pulleys.  A  simple  belt  shifter  is  provided  which  permits  of  the  two  belts 
being  moved  simultaneously.  This  avoids  the  risk  otherwise  present  of  causing 
damage  by  transmitting  the  drive  entirely  through  the  gearing  at  one  end  of  the  rolls. 
The  output  of  these  rolls  varies  from  10  to  20  cwt.  per  hour. 

Preparatory  Treatment  of  Linseed,  etc. 

Linseed,  rape  seed,  and  similar  small  seeds  require  verj^  little  special  preparation 
for  pressing.  Beyond  screening  to  remove  foreign  matter  such  seeds  have  only  to  be 
crushed  between  rolls  to  convert  them  to  meal  suitable  for  pressing. 

An  appliance  for  screening  lin.seed  and  similar  seeds,  made  by  Rose,  Downs  & 
Thompson,  Ltd.,  of  Hull,  is  illustrated  in  Fig.  8.  This  machine  consists  of  a  cast  iron 
casing  containing  a  slowly  rotating  cylindrical  screen  into  the  interior  of  which  the 
seed  is  delivered.  Inside  the  screen  is  a  fast-moving  paddle  which  throws  the  seed 
against  the  interior  surface  of  the  screen.     The  seed  is  delivered  to  the  machme  at  the 


PREPARATORY    MACHINERY    FOR    COPRA   AND    LINSEED 


19 


orifice  A,  and  is  caiTied  into  tlie  screen  hj  the  action  of  a  sliort  worm  fixed  on  the  end 
of  the  paddle  shaft.  The  screenhig  surface  is  formed  of  perforated  sheet  steel  and 
covers  the  screen  framework  from  the  line  BB  to  the  line  CC.  The  screened  seed 
fallmg  through  the  perforations  collects  \vithin  the  vee-sectioned  hopper  formed  by 
the  lower  walls  of  the  main  casmg  and  is  carried  by  a  rotating  worm  either  to  the 
outlet  D  or  the  outlet  E,  according  to  the  formation  given  to  the  worm.  The  tailmgs 
fail  to  pass  through  the  perforations  of  the  screen  and  are  delivered  through  the  gap 
left  beyond  the  line  CC  to  an  orifice  F,  divided  from  the  orifice  E  by  a  partition. 
The  machine  is  driven  from  the  right-hand  end  of  the  paddle  shaft.     The  dischargmg 


Fig.  8. — Screening  Machine  for  Linseed,  etc. — Rose,   Downs  &  Thompson. 


worm  is  driven  by  l)elt  from  the  left-hand  end  of  the  paddle  shaft  and  itself  drives  the 
cyhndrical  screen  by  chain  and  sprocket  wheels.  The  machine  illustrated  has  an 
output  of  28  to  30  cwt.  per  hour  and  requires  about  3  b.h.p.  to  drive  it.  The  paddle 
shaft  runs  at  100  revolutions  per  minute,  the  screen  at  12,  and  the  discharging  worm 
at  about  42. 

On  occasion  a  screen  of  this  type  is  required  to  deal  with  seeds  or  other  such 
material  of  varying  size,  and  to  separate  a  batch  into  two  portions  besides  the  tailings. 
For  instance,  the  left-hand  half  of  the  screened  surface  may  be  perforated  r['^  in.  mesh, 
and  the  right-hand  portion  -^  in.  The  hopper  is  then  divided  by  a  partition  such  as 
at  G,  and  the  discharging  worm  is  made  in  two  corresponding  portions,  one  right, 
the  other  left-handed.  In  this  way  the  finer-sized  seeds  are  delivered  through  the 
orifice  D,  the  coarser  at  E,  and  the  tailings  at  F. 


20        THE   PRODUCTION  AND  TREATMENT   OF  ^T:GETABLE   OILS 

A  set  of  rolls  suitable  for  crushing  linseed,  etc.,  made  by  Manlove,  Alliott  &  Co., 
Ltd.,  of  Nottingham,  is  illustrated  in  Fig.  9.  The  rolls  are  five  in  nimiber,  measure 
16  in.  in  diameter  by  42  in.  long,  are  stacked  vertically  and  are  quite  plain  on  the 
surface.  As  usual,  they  are  ground  with  great  truth  and  are  forced  on  to  their  shafts 
by  hydraulic  pressure,  being  thereafter  keyed  at  both  ends.  The  lowest  roll  is  driven 
at  both  ends  and  is  provided  mth  two  additional  pulleys,  from  which  belts  are  taken 
to  similar  sized  puUej^s  at  each  end  of  the  third  and  fifth  rolls.  The  bearings  for  all 
the  rolls  except  the  lowest  are  free  to  slide  vertically  in  their  housings.     Consequently 


Fig.  9. — EoUs  for  Linseed,  etc.  — Manluve,  Alliott. 

the  pressure  exerted  on  the  seed  being  reduced  increases  with  each  step  m  its  descent 
from  the  hopper.  The  second  and  fourth  rolls  are  driven  simply  by  the  friction 
between  them  and  their  neighbours.  The  consequent  sHp  of  these  rolls  is  reUed  upon 
to  give  the  grinding  action  which,  to  a  small  extent,  should  accompany  the  crushing 
action  of  the  machine.  Means  are  provided  whereby  the  two  upper  rolls  may  be 
held  sUghtly  raised  so  as  to  increase  the  feed.  Additional  means  are  also  provided 
whereby,  if  desired,  the  dead  weight  of  the  rolls  may  be  assisted  by  the  action  of 
tightening  screws  and  springs.  The  capacity  of  the  roils  illustrated  is  about  15  cwt. 
of  seed  per  hour. 


CHAPTER   IV 

PREPARATORY  MACHINERY  FOR  PALM  FRUIT  AND  PALM  KERNELS 

We  now  come  to  a  section  of  our  subject  concerning  which  there  is  much  discussion 
and  variety  of  opinion.  Before  proceeding  to  make  any  remarks  on  it,  we  may  direct 
the  reader's  attention  to  Fig.  10.     In  this  we  give  an  ilhistration  which  we  have  had 


Fig.   10. — Palm  Fruit,   I'oricarp,  Nuts,  Shells  and  Kernels. 

prepared  for  the  purpose  of  showing  the  fruit  of  the  oil  palm  and  its  component  parts. 
At  A  the  whole  fruit,  as  gathered  from  the  tree,  is  shown.  The  shape  and  size  of  the 
fi-uit  are,  it  will  be  noticed,  somewhat  irregular.  On  the  average  the  fiuit  is  about 
ll  in.  long  and  f  in.  maximum  width.  At  B  the  pericarp  is  to  be  seen.  The  pericarji 
has  a  smooth  outer  suiface,  but  on  the  whole  consists  of  a  mass  oi  fibres  snieaied  with 
a  thick  yellow  oil,  or,  more  correctly,  fat.  At  C  the  nuts  which  the  pericarp  surrounds 
are  shown,  while  at  Dand  E  respectively  are  indicated  the  fragments  of  the  ntit  sliells 


22        THE   PRODUmOX   AND  TREATirEXT   OF  \'EGETABLE   OILS 


and  the  nut  kernels.  The  sample  of  fniit  from  which  the  original  jthotogiaph  repro- 
duced in  this  engraving  was  prepared  was  Idndlv  supplied  to  us  by  A.  F.  Ciaig  &  Co., 
Ltd..  Caledonia  Engine  Works,  Paisley.  We  were  fortunate  in  seeming  this  sample, 
as  the  fruit  rapidly  deteiiorates  aft^r  being  gathered,  and  is  therefore  rarely  seen  in 
this  countri.  A  bunch  of  pahn  fruil  as  taken  down  fiom  the  tree  is  shown  in  Fig.  1 1, 
for  the  original  of  which  we  are  indebted  to  Messis.  Manlove.  AUiott.  Such  a  bunch 
may  weigh  round  abotit  1-4J  lb.  and  mer.sure  ab  ut  12  in.  long  by  10  in.  across.  From 
the  pericarp  B  (Fig.  lU)  pahn  oil  is  obtained,  while  fiom  the  kernels  E  a  totally  different 
oil,  palm  kernel  oil.  is  recovered.  Owing  to  the  rapid  deterioration  which  the  pericaip 
suffers  after  the  fruit  is  gathered,  it  is  impracticable  to  ship  the  whole  fruit  to  Europe 

for  treatment.  In  general,  therefore, 
the  practice  is  to  recover  the  palm  oil 
from  the  pericarp  at  or  near  the  planta- 
tions in  Africa,  and  to  send  the  nuts  or 
kernels  overseas  for  treatment  at  home. 

Treatmext  or  the  Palm  FsriT. 

L'ntU  recently,  and  still  to  a  con- 
siderable extent,  the  production  of  palm 
oil  was  in  the  hands  of  the  natives. 
The  method  they  use  is  crude.  Xot 
only  do  they  lose,  by  following  it.  from 
a  half  to  two-thirds  of  the  possible  oO 
yield,  but  the  oil  obtained  is  apt  to 
have  developed  in  it  elements  which 
lower  its  commercial  value.  The  fruit 
when  ripe,  is  deliberately  allowed  to 
ferment  in  the  presence  of  water,  so  that. 
the  hard  pericarp  may  lie  softened  and 
readily  separated  from  the  nut.  The 
separation  is  effected  simply  by  beat- 
ing the  softened  fruit  to  a  pulp,  and 
thereafter  picking  out  the  nuts  from 
The  pulp  is  then  Ixiiled  in  water,  and  the  oil.  rising  to  the 
This  method  of  working  induces  hydrolysis  in  the  oil — that 


Fig.  11. — BuBch  of  Palm  Fn. 


the  mass  by  hand. 

top,  is  skimmed  off 

is  to  say.  the  oil  combines  with  water,  and  is  changed  from  a  neutral  condition  to  an 

acid  one  by  the  breaking  down  of  its  constitution  ;nto  free  glyc^erine  and  free  fatty 

acid.     Once  hydrolysis  is  started  it  is  liable  to  continue  so  that  frequently  palm  oil  is 

received  at  its  European  destination  containing  as  much  as  5(t  per  cent,  of  free  fatty 

acids.     The  commercial  value  of  the  oil  is  proportionately  reduced. 

Many  attempts  have  been  made  to  treat  the  fruit  in  a  scientific  manner,  the  direct- 
objects  being  to  obtain  the  full  jield  of  oil  from  the  pericarp,  and  to  do  so  without 
causing  the  oil  to  decompose,  or.  to  use  the  technical  tenn.  to  hydrolyse.  It  is  obvious 
that  to  prevent  hydrolysis  the  fruit  must  be  subjected  to  a  treatment  which  in  no  waj 
calls  for  its  being  placed  in  contact  with  water  in  any  form.  This,  the  ideal  process, 
is  commoiJy  spoken  of  as  the  "  dry  '"  method.  Certain  "  diy  "'  methods,  notably  a 
German  one.  have  been  proposed,  and  have  received  some  apphcation  which  have 
not  come  up  to  the  ideal  standard,  for  at  some  stage  or  other  water  or  steam  has  been 
used  to  assist  the  recovery  of  the  oil  or  the  separation  of  the  pericarp  from  the  nut. 


MACHINERY  FOR  PALM  FRUIT  AND  PALM  KERNELS 


23 


Separation  of  the  Pericarp. 

The  chief  difficulty  imdoubtedly  lies  in  the  effective  separation  of  the  pericarp 
without  waituig  for  it  to  soften,  eitlier  by  natural  deterioration  or  by  fermentation 
in  presence  of  water.  What  may  be  called  a  compromise  process  may  first  be  described. 
The  machinery  for  this  process  has  been  supplied  by  Manlove,  Alliott  &  Co.,  Ltd.,  of 
Nottingham,  and  we  are  informed  that  good,  if  not  ideally  satisfactory  results  have 
been  obtained  with  it.  Under  this  method  of  worldng  the  fruit  freshly  gathered  is 
taken  to  a  machine  provided  with  a  revolving  shaft,  on  which  are  mounted  several 
bayonet-like  luiives.     Here  the  fruit  with  its  nuts  is  cut  and  churned  up  into  a  pulp. 


The   Engineer" 


Fui.   12.  —  Fairfax'.s  Depericarping  Machine. 


The  mass,  sufficiently  reduced,  is  then  placed  in  a  cage  pre.ss,  and  pressure  applied  to 
it  until  the  nuts  are  heard  to  begin  to  crack.  The  oil  which  ffows  away  is,  of  course, 
of  good  quality,  but  in  quantity  does  not  represent  the  full  oil  content  of  the  pericarp. 
The  half-pressed  material  is  therefore  boiled  up  with  water  to  recover  the  remaining 
oil,  and  to  complete  the  separation  of  the  pericarp  from  the  nuts.  The  oil  skimmed 
off  the  boilmg  water  is  naturally  of  an  inferior  quahty  to  that  running  from  the  press. 
Palm  oil  is  a  very  valuable  substance,  and  would  be  still  more  so  were  it  possible 
to  obtain  it  in  good  condition  in  large  and  regular  supplies.  Consequently  we  find 
that  much  attention  has  been,  and  is  being,  devoted  to  the  design  of  a  satisfactory 
depericarping  machine  for  palm  fruit  which  will  permit  the  whole  pericarp  to  be  treated 
by  a  truly  dry  process.     To  Messrs.  A.  V.  Craig,  of  Paisley,  we  are  indebted  for  the 


24         J'HE   PRODUCTION   AND  TREATMENT   OF   \T:GETABLE  OILS 

particulars  and  Olustrations  which  we  are  enabled  to  give  of  their  "  Caledonia  "  dry 
process,  and  of  the  macliines  designed  to  give  it  effect. 

The  depericarpLiig  machine  used  under  this  process  is  the  patented  invention  of 
Mr.  H.  G.  Fairfax,  and  is  illustrated  in  Fig.  12.  Li  Fig.  13  we  give  a  working  drawing 
of  the  same  invention,  as  carried  out  on  practical  lines  hv  Messrs.  Craig.  The  macliine 
consists  essentialh'  of  two  parts,  namely  a  rotathig  table  A  (Fig.  12),  and  a  rotating 
cover  B,  the  former  running  quickly  in  one  direction  and  the  latter  slowly  in  the 
opposite  direction.  The  table  carries  a  series  of  closely  spaced  curved  blades  or 
abraders  C.  The  cover  is  formed  with  a  series  of  wider  spaced  oppositeh^  cm^ved 
ribs  D.  The  fruit  is  fed  into  the  cover  through  the  annulus  F.  and  passing  outwards 
is  stripped  of  its  pericarp  by  the  blades  C.  The  counter  curvature  cf  the  blades  C 
and  the  ribs  D  has,  of  course,  an  important  influence  on  the  stripping  action.  The 
loosened  peiicarp  falls  between  the  blades  C  and  is  at  once  ejected  outwards  by  cen- 


Tme   Engineer' 


Fio.  13. — Depericarping  Machine^for  Palm  Fruit — A.  F.  Cruig. 


trifugal  force  over  the  edge  of  the  table.  Here  it  falls  into  the  receptacle  F,  which,  to 
facilitate  the  movement  of  the  pericarp,  is  steam  heated.  It  will  be  noticed  that  the 
steam  jacket  G  also  extends  beneath  more  than  half  the  effective  part  of  the  blades  C. 
The  nuts  ure  too  large  to  pass  between  the  blades  on  the  table.  Instead  they  are  shot 
out  through  holes  round  the  upstanding  lip  of  the  machine  casing,  and  are  thus  collected 
separately  from  the  pericarp.  Any  oil  which  may  be  set  free  during  the  stripping  of 
the  pericarp  is  shot  against  a  screen  H  and  flows  away  down  the  outlet  J. 

The  nuts  as  they  leave  the  depericarpmg  machine  may  have  small  portions  of  the 
pericarp  still  adhering  within  the  irregularities  of  their  shells.  To  recover  such  portions 
the  nuts  may  be  passed  through  the  patented  brush  macliine  illustrated  in  Fig.  14. 
This,  like  the  depericarping  macliine  above  described,  is  made  by  Messrs.  Craig,  of 
Paisley.  It  consists,  in  essence,  of  two  cylindrical  brushes,  3  ft.  long  and  about  7g  in. 
in  diameter,  revolving  side  by  side  at  300  revolutions  per  minute,  beneath  a  casing  or 
cover  embracing  the  upper  portions  of  the  brushes.  The  brush  spmdles  rotate  in 
bearings  fixed  to  the  casing,  and  are  driven  through  bevel  gearing  from  a  shaft  jour- 
nalled  cross-wise  on  the  maLu  frame  of  the  maciiine.     The  casing  is  also  joumalled 


MACHINERY    FOR    PALM    FRTIIT    AND    PALM    KERNELS 


25 


to  tliis  cross  shaft,  so  that  it  and,  with  it, 
the  brushes  may  be  set  longitudinally  to 
any  desired  inclination.  It  is  fixed  in 
position  at  the  other  end  by  means  of  bolts 
passed  through  one  or  otlier  of  a  series  of 
holes  formed  in  a  projection  on  the  main 
frame.  At  the  drivuig  end  of  the  machine 
the  casmg  is  provided  with  a  hopper,  into 
which  the  nuts  are  fed.  From  this  the  nuts 
enter  one  or  other  of  ten  gi'ooves  formed 
on  the  miderside  of  the  casing.  The  in- 
clination of  the  casing  causes  the  nuts  to 
travel  do\\Ti  these  grooves  to  the  outlet  end, 
and  in  so  doing  they  are  timied  and  brushed 
all  over  by  the  brush  bristles,  which  form, 
as  it  were,  the  fourth  side  of  the  gi'ooves. 
The  pericai"p  fragments  removed  by  the 
brushes  fall  into  a  hopper  between  the 
main  frame  uprights.  The  cleaned  nuts 
emerging  from  the  ends  of  the  grooves  are 
caught  in  a  separate  hopper.  The  macliine 
is  designed  nominally  to  deal  with  about 
12  cwt.  of  nuts — say,  134,000  nuts — per 
hour.*  The  ten  grooves  hold  at  any  one 
time  400  nuts.  The  nuts  are  in  contact 
with  the  brushes  for  about  11  seconds 
each.  By  altering  the  inclmation  of  the 
brushes  and  casmg  the  output  can  be 
adjusted  wdthin  certain  limits.  The  two 
brushes  revolve  m  opposite  directions,  and 
are  covered  ^^^th  "  wire  cloth  "  formed  of 
leather,  in  which  are  fixed  projecting  wires 
as  indicated  in  the  sketch.  Fig.  15. 

Treatment  of  the  Nut.s. 
The  pericarp  thus  recovered  is  pressed 
at  once.  The  nuts  as  cleaned  by  the 
b.ushmg  machme  are  dried  either  naturally 
or  artificially  to  loosen  the  kernel  within 
the  shell.  They  have  then  to  be  cracked 
open  and  the  kernel  separated  from  the 
shell  fragments.  A  cracking  and  separating 
machine,  made  by  ^Messrs.  Craig,  of  Paisley, 
is  illustrated  in  Fig.  16.  The  hopper  of  this 
machine  is  vee-shaped  in  section,  and  is 
provided  internally  with  an  inverted  vee- 
shaped  surface,  which  divides  the  nuts  into 

*  These  figures  imply  that  the  nuts  run  at 
about  11,000  to  the  hundredweiglit.  They  vary 
in  size  and  sometimes  number  as  few  as  5,500  to 
the  hundredweight. 


26 


THE   PRODUCTIOX   AND   TREATMENT   OF   M^GETABLE   OILS 


two  streams.  Each  such  stream  passes  down  a  pipe  A  east  on  the  outside  of  a  semi- 
cylindrical  casing,  which  contains  a  drum  driven  at  a  high  speed,  about  1,000  revolu- 
tions per  minute.  The  nuts  fall  into  tl.e  interior  of  the  drums  and  are  shot  out  by 
centrifugal  force  through  slots  in  the  drum  periphery.  Striking  forcibly  against  the 
inner  wall  of  the  surrounding  casings,  the  shells  are  cracked  open,  and  Avith  the  kernels 
fall  to  the  foot  of  the  casmgs.  whence  they  are  conducted  on  to  the  shaking  separator, 
disposed  between  the  legs  of  the  machine  frame.     The  separator  consists  of  an  inclined 


_.a^ 


p^  Qrir^jr'  |L 


^ 


3 


B^^n— a 


Plan  with  Hopper  S  Platform  removed 
"the   Encineeb" 

Fig.  16. — Palm  Xut-ciacking  and  Separating  Machine — Craig. 

tray,  the  bottom  of  which  is  formed  with  a  special  surface.  At  the  lower  end  it  is 
overhmig  on  s\Ninging  links,  the  pivot  points  of  which  can  be  varied  to  give  the  tray 
the  required  inclination.  At  the  higher  end  it  is  journalled  to  a  short-throw  crank- 
shaft driven  at  250  revolutions  per  minute.  The  bottom  of  the  tray  is  not  perforated. 
The  shaking  action,  combined  with  the  special  construction  of  the  bottom  surface, 
results  in  the  kernels  being  passed  to  one  end  of  the  tray  while  the  shell  fragments 
pass  to  the  other.  Falling  over  the  ends  they  are  collected  in  hoppers.  The  shells 
can  be  used  as  fuel,  either  under  a  boiler  or  in  a  gas  producer. 


MACHINERY    FOR    PALM    FRUIT    AND    PALM    KERNELS  27 

Li  general  the  kernels  .are  shippefl  to  oil  mills  in  Europe  or  elsewhere.  Their 
preliminary  treatment  closely  agrees  with  that  accorded  to  copra,  much  the  same 
shreddmg  and  reducing  rolls  being  used  to  convert  them  to  the  form  of  meal.  Certain 
considerations,  however,  have  led  the  factories  in  Africa  to  contemplate  undertaldng 
the  work  of  recovering  palm  kernel  oil  within  their  own  walls.  The  chief  of  these  is 
the  fact  that  pahn  fruit  is  not  available  all  the  year  round,  so  that  during  the  "  off  " 
season,  if  palm  oil  alone  is  dealt  with,  the  expensive  presses  and  other  plant  must  lie 
idle.     By  a  little  additional  capital  expenditure  the  factory  can  be  readily  fitted  for 


-s^B^  -4^-     i[^-     |a 


Plan   of   Ground   Fl, 


Dej)eri  carpers 
Brfjsh  Msrhmes 
Nut  Crac±c_ 


Herrel  Separator 
ficdacrnQ  Milt 
'Shrrddma  Rolls 
'Q  Kettle _  . 


Accumulator 


Fig.   17. — Palm  and  Palm  Kernel  Oil  Mill— Craig. 

treating  the  kernels,  so  making  it  possible  to  fill  in  the  otherwise  idle  period,  and  to 
keep  the  staff  together. 


A  Palm  and  Palm  Kernel  Oil  Factory. 

In  Fig.  17  we  give  the  general  lay  out  of  an  African  mill  working  on  Messrs.  Craig's 
"  Caledonia  "'  dry  system.  The  equipment  of  this  mill  includes  preliminaiy  screens 
for  removing  any  sand  or  other  material  which  the  natives  may  be  tempted  to  mix 
with  the  fruit,  three  depericarping  machines,  three  brush  machines,  six  combined  nut- 
cracking  and  kernel-separating  machines,  three  reducing  mills,  three  sets  of  shredding 
rolls,  three  heating  kettles,  and  three  ciushing  presses.  The  latter  are  of  the  bar  cage 
t3'pe,  to  be  described  in  a  later  chapter,  and  have  each  three  .sections,  namely,  a  preli- 
minary, an  intermediate,  and  a  tuiishing  press.  Equipment  is  also  provided  for  sealing 
up  the  palm  oil  in  tins  as  soon  as  it  has  been  expressed  from  the  pericarp.  The  design 
of  this  factory  is  such  as  to  enable  it  to  deal  with  about  50  tons  of  fresh  fruit  daily 
or  with  the  kernels  derived  from  about  100  tons  of  nuts. 


28        THE   PRODUCTION  AND  TREATMENT   OF  VEGETABLE   OILS 

As  showmg  the  importance  of  oil  palm  fruit,  we  may  remark  that  in  1913  the 
United  Kingdom  imported  palm  oil  to  the  value  of  £2,326,842.  In  the  same  year 
Germany  imported  palm  kernels  to  the  value  of  £3,314,278,  while  other  countries, 
including  our  own,  took  together  kernels  valued  at  £1,918,974.  The  outbreak  of  war 
greatly  affected  matters.  In  1914  our  imports  of  palm  kernels  were  valued  at 
£1,411,928,  and  in  1915  at  about  £2,500,000.  Even  so  the  palm  fruit  industry  may 
yet  be  said  merely  to  be  in  its  infancy. 


CHAPTER  V 

PREPARATORY  MACHINERY  FOR  COTTON  8EED  AND  CASTOR  SEED 

Cotton  seed,  as  we  remarked  in  our  second  chapter,  is,  so  far  as  the  oil  niillmg 
industry  is  concerned,  of  two  varieties,  one  being  the  black  Egyptian  seed,  the  husk 
of  which  as  received  is  practically  free  from  adhering  cotton  fibre,  and  the  other  the 
white  American  or  Indian  seed,  to  which  quite  a  considerable  quantity  of  cotton  fibre 
may  be  adherent.  The  "  white  "  seed  is  white  merely  by  virtue  of  the  adhering  lint. 
In  Fig.  18  wc  reproduce  a  photograph  of  some  samples  of  the  two  varieties  of  cotton 


l>"iG.  IS. — American  aud  Kgyjitiau  Cotton  Seed. 

seed,  kindly  supplied  to  us  by  Rose,  Downs  &  Thompson,  Lt  1.  At  A  the  American 
seed  is  showii,  and  at  B  the  Egyptian.  The  husks  C  and  D  respectively  are  hard 
and  tough,  the  American  being,  if  anything,  harder  and  tougher  than  the  Egyptian. 
The  oil-bearing  kernels  E,  F,  are  soft  yellow  or  whitish  bodies  which  can  readily  be 
crushed  between  the  fingers.  The  American  kernels  are  di.stinctly  smaller  than  the 
Egyptian.     The  engraving  is  facsimile  as  to  the  size  of  the  seeds. 

La  this  comitry  it  is  a  common  custom  in  the  production  of  cotton  .seed  oil  simply 
to  reduce  the  seed  as  received  between  rolls  and  then  to  press  the  resultant  meal  in 
the  usual  way.  In  this  way  the  husks  and,  in  the  ca.se  of  the  American  seed,  the 
adhering  cotton  lint  pass  into  the  cake.  There  does  not  appear  to  be  any  serious 
agricultural  objection  to  this  course,  for  cotton  seed  cake  is  in  great  favour  as  a  cattle 
food.  An  excessive  amount  of  lint  in  the  case  of  the  American  .seed,  such  as  is  some- 
times fomid  on  seed  that  has  been  badly  ginned,  would,  undoubtedly,  lower  the  value 


30 


THE   PRODUCTION   AND   TREATMENT   OF   VEGETABLE   OILS 


of  the  resultant  cake.  Moreover,  the  excess  lint  has  a  distinct  commercial  value  as 
cotton.  Hence,  for  two  reasons  it  may  well  pay  the  oil  mills  handling  American 
cotton  seed  to  re-gin  or  de-lint  it  as  a  preliminary  to  treating  it  in  the  rolls  and  presses. 


De-linting. 

A  cotton  seed  de-linting  machine  as  erapljoyed  at  an  oil  mill  is  almost  identical 
lith  a  cotton  gin  as  employed  by  the  cotton  grower.     In  Fig.  19  we  give  a  drawing 

the  original  of  which  was  supplied  to  us 
by  Rose,  Downs  &  Thompson,  Ltd., 
showing  the  general  arrangement  of  a 
cotton  seedde-linter.  The  seed  delivered 
to  the  machine  at  A  is  admitted  by  a 
power-driven  feed  roller  in  an  even 
stream  into  the  seed  box  B.  One  wall  of 
this  box  consists  of  a  grating  C  through 
which  project  the  tips  of  a  large  number 
of  fine-toothed  circular  saws.  These 
saws  number  usually  106,  and  are  spaced 
apart  on  the  shaft  D  by  means  of  thin 
cast-iron  distance  washers.  The  saw 
cylinder  runs  at  375  revolutions  per 
minute.  The  seed  in  the  seed  box  is 
churned  up  by  the  saws,  the  teeth  of 
which  catch  on  the  lint  and  remove  it 
in  great  part  from  the  seeds.  The  de- 
linted  seed  escajies  from  the  shoot  E 
under  the  control  of  a  hinged  regulating 
board,  not  shown  in  the  drawing.  The 
lint  adhering  to  the  saws  is  picked  off  the 
teeth  by  a  circular  brush  mounted  on 
the  shaft  F  and  revolving  at  about  1,360 
revolutions  per  minute.  From  this  brush 
the  lint  is  deflected  into  a  flue  G  by 
means  of  an  air  draught  produced  by  a 
fan  on  the  shaft  H.  The  draught  is 
regulated  by  the  damper  J  and  the 
handle  K.  From  the  flue  the  lint  is 
delivered  into  a  "  condenser "  L,  a 
casing  containing  a  revolving  cylindrical 
cage  of  wire  cloth,  on  which  the  lint 
collects  as  a  roll  and  from  which  it  is 
removed  from  time  to  time.  This 
machine  absorbs  from  4  to  8  b.li.p.,  and 
can  treat  from  3  to  20  tons  of  seed  per 
twenty-four  hours,  according  to  the  nature  of  the  seed  and  the  extent  to  which  it  is 
desired  to  de-lint  it  On  the  average  it  may  be  expected  that  round  about  20  lb.  of 
lint  will  be  obtained  from  a  ton  of  seed.  The  presence  of  iron  particles  amongst  the 
seed  fed  to  the  machine  has  to  be  guarded  against,  because  of  the  very  destructive 
effect  such   material   would   have  on   the   saw   teeth.      It  is,  therefore,  a  common 


L   Engineer"  Plan  Swain    Sc. 

Fig.  19. — Cotton  Seed  De-linter  -Rose,  Downs. 


MACHINERY    FOR    COTTON    SEED   AND    CASTOR    SEED 


31 


32        THE  PROBUCTIOX  AXD  TREATilENT   OF  VEGETABLE   OILS 

practice  to  embody  in  the  seed  box  a  series  of  electro-magnets  over  which  tha  setd 
is  compelled  to  pass  before  it  reaches  the  saws. 

Decorticating  Cotton  Seed. 

Following  American  practice,  it  is  becoming  common  in  this  countiy,  in  some 
cases,  to  remove  the  husks  or  cortex  of  the  seed?  before  crushing  and  pressing  them. 
In  this  way  the  kernels,  or  "  meats  ''  as  they  are  called,  alone  are  pressed.  The 
advantages  of  this  practice  lie  in  the  freedom  from  discoloration  of  the  oil,  otherwise 
liable  to  be  produce:!  by  the  colouring  matter  in  the  husks,  the  improved  quality  of  the 
cake,  and  the  increased  output  of  oil  obtained  from  a  press  of  given  size. 

A  decorticating  machine  for  cotton  seed,  made  by  Rose  Downs  &  Thompson, 
Ltd..  is  shown  in  sectional  elevation  in  Fis:.  20.     The  machine  mav  be  described  a-< 


Fig.  21. — Castor  Seed — Pods,  Beans  and  Kernels. 

consisting  of  a  rotating  barrel  carrying  ten  knives  crosswise  on  its  periphery,  and  of  a 
fixed  "  breast  '"  carrying  three  stationary  luiives  similarly  disposed  crosswise.  The 
seed  is  fed  on  to  the  barrel  from  an  overhead  hopper  by  means  of  a  power-driven  fluted 
feed  roll,  working  in  conjunction  with  a  hand-regulated  shutter  across  the  hopper 
mouth.  The  "  breast  ""  is  made  in  four  sections,  the  divisions  being  coincident  with 
the  planes  of  the  central  lines  of  the  three  "  breast "'  knives.  The  seed  falling  on  to 
the  rotating  barrel  is  caught  between  the  rotating  and  fixed  knives.  The  husks  and 
kernels  together  are  carried  round  to  the  lower  edge  of  the  "  breast  '"  and  are  there 
collected.  This  machine  is  made  in  several  sizes.  That  size  illustrated  has  an  output 
of  about  10  cwt.  per  hour,  and  to  drive  it  absorbs  some  6  b.h.p.  The  knife  barrel 
in  this  case  runs  at  1..500  revolutions  per  minute. 

Considerable  mechanical  interest  attaches  to  the  method  adopted  by  the  designers 
of  this  machine  for  carrying  the  ban-el  blades.  Three  conditions  have  to  be  met. 
First,  the  knives  have  to  be  readily  adjustable  radially  to  suit  possible  variations  in 
the  size  of  seed  deli%'ered  to  the  machine  for  treatment.  Secondly,  the  knives  have 
to  Ije  easily  removable,  so  that  the\-  may  be  taken  out  and  sharix;ned.     Thirdly,  the 


MACHINERY  FOR  COTTON  SEED  AND  CASTOR  SEED 


33 


luiives  must  he  fastened  in  some  particularly  secure  manner,  to  withstand  the  centrifugal 
force  on  tliem  arising  from  their  high  speed  of  rotation.  To  fulfil  these  requirements, 
no  attempt,  it  will  be  seen,  is  made  to  fix  the  knives  directly  to  the  barrel  itself.  The 
barrel  is  simply  slotted  to  allow  the  knives  to  pass  through  it.  In  each  side  frame  of 
the  machine  a  circular  central  hole  is  formed.  Through  these  holes  the  ends  of  the 
knives  project.     Beyond  each  frame  a  flanged  and  slotted  disc  is  fixed  to  tlie  banel 


The    Engineer" 


Fig.  22. — Castor  Seed  Sheller— Rose,   Downs  &  Thompson. 

shaft.  Tiie  ends  of  the  knives  are  carried  through  the  slots  in  these  discs  and  are 
gripped  in  the  slotted  heads  of  bolts  radiating  inwards  from  the  disc  flanges.  In  use, 
the  flanged  discs  are  enclosed  within  a  stationary  siieet  metal  casing  to  prevent  accidents. 
A  similar  method  is  adopted  for  securing  the  "  breast  "  knives  in  place.  In  this  case 
the  slot-headed  bolts  are  attached  to  bosses  projecting  from  the  main  framing. 

The  further  treatment  of  cotton  seed  requires  no  special  remark.  It  is  crushed, 
preparatory  to  pressing,  in  rolls  closely  similar  to  or  identical  with  those  used  for 
linseed  or  even  copra,  see  Figs.  4,  5  and  9,  Chapter  III. 


34  THE  PRODUCTION   AXD  TREA-OnrST   OF   VEGETABLE   OILS 


"t-e    E-.csEta" 


Fig.  23.— <Tastor  Seed 


:r  and  Separator — ^Bose,  Downs  & 


MACHINERY  FOR  COTTON  SEED  AND  CASTOR  SEED 


35 


Castor  Sked. 
The  distinguishing  feature  of  castor  seed  as  an  oil-bearing  substance  lies  in  the 
fact  that  the  portion  which  carries  the  oil  is  enclosed  within  two  outer  casings.  Fig.  21, 
prepared  from  samples  kindly  supplied  by  Rose,  Downs  &  Thompson,  Ltd.,  shows 
the  seed  and  its  component  i)arts.  At  A  the  seed  as  grown  is  illustrated.  The  pod, 
it  will  be  gathered,  is  in  three  sections,  B.  The  removal  of  the  husk  C  from  either 
of  these  sections  reveals  a  deep-coloured  prettily-marked  bean  D.     The  cortex  or 


i'j/i^Orlvinq  pulley  II ZRe^.  I    I    I 


The   Enoineer  Sw»in    Sc. 

Fig.  24. — Castor  Seed  Deoorticator  &  Separator — Robert  Middleton. 

shell  E  of  these  Ijeans  is  thin  and  brittle,  and  encloses  the  white  oil-bearing  kernel  F. 
The  engraving  is  facsimile  as  to  size. 

Shelling. 
The  first  step  in  the  preparation  of  the  seed  for  pressing  is  the  removal  of  the  outer 
shell  or  pod.  A  machine  for  this  purpose,  a  castor  seed  sheller,  made  by  Rose,  Downs 
&  Thompson,  Ltd.,  is  represented  in  Fig.  22.  The  .seeds  are  fed  into  a  small  hopper 
A  at  the  top  of  the  machine,  and  are  thence  carried  bj'  a  rotating  worm  between  a 
pair  of  discs  B.  The  distance  between  these  discs  can  be  regulated  by  the  means 
indicated  to  suit  requirements.  The  pods,  rubbed  between  the  discs,  have  their  outer 
casings  broken,  and  escaping,  fall  through  a  special  distribution  device  into  the  hopper 


3(5         THE   PRODUCTION   AND   TREATiEEXT   OF    VEGETABLE   OILS 

C,  and  thence  past  a  hinged  regiilating  flap,  across  the  channel  D  into  another  hopper  E. 
While  the  stream  is  crossing  the  channel  D  it  meets  a  blast  of  air  from  the  fan  F.  The 
force  of  the  blast  is  regulated  so  that  the  lighter  material  only,  the  fragments  of  the 
outer  husk,  may  be  carried  away,  as  at  G,  into  a  suitable  collecting  chamber.  The 
heavier  portions,  the  beans  with  what  husk  may  yet  adhere  to  them,  pass  from  the 


Fig.  25. — Castor  Seed  Decorticator  and  Separator — Bobert  Middleton. 

hopper  E  to  a  pair  of  rolls  H,  the  distance  apart  of  which  is  carefully  adjusted  to  suit 
requirements.  Leaving  these  rolls,  the  beans  and  husk  fragments  fall  on  to  a  shaking 
separator  J.  Leaving  this  at  K,  the  material  in  descending  meets  a  blast  of  air  from 
a  second  fan  L.  This  blast  carries  away  ^^^th  it  down  the  passage  M  the  lighter  frag- 
ments of  the  outer  pod  yet  remaining  in  the  stream,  but  is  not  sufficiently  strong  to 
prevent  the  beans  from  descending  into  the  hopper  N.  The  speeds  of  the  various 
parts  of  this  machine  are  marked  on  the  drawing.  The  example  illustrated  has  an 
output  of  10  to  20  cwt.  per  hour,  and  absorbs  6  to  8  b.h.p. 

Decorticatixg  Castor  Seed. 
The  machine  just  described  removes  the  outer  husk  of  the  seed.     Doubtless  it 
maj'  remove  some  of  the  inner  shell  as  well,  but  for  this  purpose  it  is  usual  to  pass  the 


MACHINERY    FOR    COTTON    SEED    AND    CASTOR    SEED  37 

seed  through  a  special  decorticating  machine  after  it  has  gone  through  the  sheller. 
A  combined  decorticator  and  separator  for  castor  seed,  made  by  Rose,  Downs  & 
Thompson,  is  illustrated  in  Fig.  23.  In  this  the  beans  are  distributed  from  a  hopper, 
provided  with  a  Huted  feed  roll  and  a  hand-regulated  shutter  plate.  The  beans  fall 
and  are  cracked  between  a  pair  of  cylindrical  rolls,  the  space  between  which  can  be 
suitably  regulated  by  hand.  Leaving  the  rolls,  the  l:)roken  shells  and  kernels  fall 
on  to  a  shaking  separator.  This  separator  consists  of  two  series  of  contra-sloping 
trays,  extending  between  and  united  to  a  pair  of  vertical  side  frames.  The  frames 
referred  to  are  hung  by  means  of  eight  flat  steel  springs  from  the  main  framing  of  the 
machine,  four  of  the  springs  being  within  the  main  frames,  and  four,  at  a  lower  level, 
being  external  to  them.  The  separator  is  vibrated  by  means  of  a  pair  of  flexible 
connecting  rods  lying  outside  the  main  frames,  and  coupled  up  to  a  short-throw  crank- 
sluxft  extending  across  the  main  frames  at  the  right-hand  end,  as  seen  in  the  elevations 
in  the  engraving.  An  air  trunk  with  a  fan  at  its  foot  is  arranged  between  the  main 
frames  at  the  crankshaft  end.  This  trunk  has  four  separate  orifices,  the  blasts  from 
which  can  be  controlled  independently  by  shutters  operated  by  racks  and  hand-wheels. 
The  shells  and  kernels  falling  from  the  rolls  travel  under  the  shaking  action  from  one 
tray  to  the  next  in  the  series.  The  kei-nels  complete  the  whole  coui'se,  and  fall  off  the 
separator  at  the  right-hand  end  of  the  lowest  tray.  The  lighter  portions  of  the  beans, 
the  shell  fragments,  under  the  action  of  the  air  blast,  fail  to  complete  the  whole  course, 
and  are  carried  off  over  the  left-hand  end  of  one  or  other  of  the  trays  into  a  vertical 
passage,  from  the  foot  of  which  they  are  eventually  discharged.  Doors  are  provided 
in  the  outer  wall  of  this  passage  to  regulate  the  egress  of  the  air  blast. 

The  output  of  the  size  of  machine  illustrated  is  20  cwt.  of  beans  per  hour.  Seven 
brake  horse-power  is  absorbed  in  driving  it.  The  crushing  rolls  rmi  at  100  revolutions 
per  minute,  the  separator  shaker  shaft  at  500,  the  feed  roll  at  120,  and  the  fan  at  1,000. 

It  may  be  remarked  that  the  practice  of  freeing  the  castor  seed  kernel  from  its 
inner  or  second  coverhig  is  not  by  any  means  universal.  It  is  more  or  less  necessary, 
if  a  good,  clear  quality  of  hot-drauii  oil  is  desired,  but  for  many  purposes  the  oil  obtained 
by  pressing  the  beans  with  only  the  outer  pod  removed  is  found  sufficiently  good  to 
justify  the  practice. 

Another  castor  seed  decorticator — made  by  Robert  Middleton  &  Co.,  of  Sheepscar 
Foundry,  Leeds — is  shown  m  Figs.  24  and  25.  The  design  is  considerably  different 
from  that  illustrated  in  Fig.  23,  but  the  prmciple  of  action  is  much  the  same.  The 
hopper  from  which  the  seed  passes  to  the  cracking  rolls  is  provided  ■with  the  usual 
.screw-adjusted  flap  and  power-driven  feed  roll.  The  cracking  rolls  are  8  in.  in  diameter, 
are  of  cast  iron,  turned  and  fluted,  and  are  driven  at  differential  speeds.  They  are 
joumalled  in  horizontally  shding  bearings,  the  distance  between  the  rolls  being  regulated 
by  means  of  a  pair  of  wedge-headed  bolts.  A  pair  of  weighted  bell-crank  levers  ser\^e 
to  regulate  the  pressure  exerted  by  the  rolls  on  the  seed  in  the  manner  indicated  in 
Fig.  24.  From  the  cracking  rolls  the  kernels  and  husks  fall  on  to  a  shaking  separator 
carried  on  spring  rods,  and  vibrated  by  a  short-throw  crankshaft  running  at  250  revolu- 
tions per  minute.  On  the  shaker  the  charge  is  tossed  about,  and  those  poitions  of  the 
cracked  shells  which  may  yet  be  adhering  to  their  kernels  are  separated  therefrom. 
Towards  the  lower  end  of  the  shaker  the  charge  passes  on  to  a  perforated  portion  of 
the  bottom.  Through  this  the  shells,  kernels,  and  dust  pass.  Sticks,  portions  of  the 
outer  husks  and  other  lai'ge-sized  extraneous  matter  pass  across  it,  and  are  discharged 
through  an  opening  in  the  bottom  into  a  shoot.  The  .shells,  kernels,  and  dust  leaving 
the  shaker  fall  mto  a  trunk,  up  which  a  blast  of  air  is  blowia  from  a  fan  at  the  foot. 
The  kernels,  or  the  majority  of  them,  succeed  in  passing  across  this  trunk,  and  fall  into 


38        THE  PRODUCTION   AXD   TREAT]WENT   OF  ^TIGETABLE   OILS 

an  outlet  shoot.  The  ligliter  portions  are  carried  by  the  air  blast  into  a  dust  chamber. 
At  the  foot  of  this  chamber  is  a  partition  2  ft.  high,  the  position  of  which  is  adjusted 
so  that  any  kernels  carried  over  ^^ith  the  blast  shall  fall  on  one  side  of  it,  wliile  the  dust 
and  shells  fall  on  the  other.  The  machine  illustrated  can  deal  with  7|  cwt.  of  seed 
per  hour,  and  absorbs  in  its  driving  about  3  li.p. 


CHAPTER   VI 

SOME   SPECIAL  FORMS   OF   REDUCTION   MACHINERY 

The  preceding  chapters  should  have  given  the  reader  some  idea  of  how  certain 
important  oil-bearing  vegetable  substances  are  prepared  for  pressing,  and  of  the  design 
and  working  of  tiie  special  machinery  used  for  this  preparation.  We  have  by  no 
means  exhausted  this  section  of  our  subject,  but  we  must  now  conclude  it  by  describing 
the  construction  ot  a  few  additional  and  more  or  less  specialised  machines  used  for 
the  reduction  of  various  jirepared  or  unprepared  seeds,  fruit,  etc.,  to  the  form 
of  meal. 

Horizontal  Seed  Rolls. 

The  rolls  employed  for  reducing  copra,  palm  kernels,  linseed,  cotton  seed,  castor 
seed,  and  so  on,  are,  generally  speaking,  of  much  the  same  design  whatever  the  material 
treated  may  be.  In  Chapter  III.  we  illustrated  and  described  several  typical 
examples.  In  Fig.  26  we  give  a  view  of  a  special  set  of  rolls  constructed  by  Robert 
Middleton  &  Co.,  Sheepscar  Foundry,  Leeds,  and  intended  particularly  for  crushing 
ca.stor  seeds  and  similar  material.  The  rolls,  two  n  number,  are  in  this  instance 
arranged  s'de  by  side  and  not  vertically,  as  they  so  frequently  are.  They  are  of  chilled 
or  oti.er  hard  cast  iron,  lightly  fluted  with  spirals,  and  measure  16  in.  in  diameter  by 
30  in.  in  length.  Their  distance  apart  is  adjustable  within  limits.  One  of  the  ro'ls 
runs  in  fixed  bearings,  while  the  bearings  of  the  other  are  slidable  and  are  acted  upon 
by  strong  springs  which  permit  the  rolls  to  open  if  the  feed  is  too  heavy,  or  if  any  hard 
foreign  substance  is  encountered  in  the  seed.  The  rolls  are  driven  by  heavy  cast  iron 
gearing  and  run  at  from  80  to  100  revolutions  per  minute.  A  steel  scraper  is  provided 
for  each  roll  and  is  held  up  to  its  work  by  means  of  a  pair  of  forged  levers  and  cast-iron 
weights.  The  cast  iron  hopper  situated  over  the  opening  between  the  two  rolls  is 
fitted  with  the  usual  power-driven  feed  roller  and  hand-regulated  feed  shutter.  About 
10  tons  of  material  can  be  treated  per  day  of  ten  hours  with  these  rolls.  To  drive 
them  lequires  about  4  h.p.  Similar  rolls  are  made  by  Messrs.  Middleton  for  treating 
copra,  pabn  kernels,  etc.,  but  for  such  heavy  material  two  pairs  of  rolls,  one  above 
the  other,  are  provided. 

Wliile  it  is  generally  true  that  rolls  such  as  the  above,  and  those  previously 
described,  are  in  extensive  employment  for  reducing  oil-bearing  seeds,  etc.,  to  the 
form  of  meal,  it  is  to  be  noted  that  various  other  forms  of  crushing  or  disintegrating 
machinery  are  made  and  are  in  employment.  That  efforts  should  be  made  to  i)rovide 
alternative  means  of  reducing  seed  to  meal  is  to  be  expected,  for  the  practice  of  using 
rolls  involves,  more  especially  in  the  case  of  heavy  material  such  as  copra  and  palm 
kernels,  the  expenditure  of  a  considerable  amount  of  power,  and  results  in  the  space 
occupied  by  the  reducing  plant  being  greater  perhaps  than  it  need  be.  We  have 
already  illustrated  one  form  of  alternative  to  a  set  of  rolls,  namely,  the  preliminary 
breaking  machine  made  by  Messis.  Manlove,  Alliott  and  shown  in  Fig.  3,  Chapter  JIJ 
Four  other  alternatives  will  now  be  referred  to. 


40         THE   PRODUCTION   AND  TREATMENT   OF  VEGETABLE   OILS 


Fig.  26. — Horizontal  Seed  Rolls— Robert  Middleton. 


Fig.  27. — Edge  Ruuuer — Robert  Middleton. 


SOME    SPECIAL    FORMS    OF    REDUCTION    MACHINERY  41 


Edge  Runners. 


The  first  of  tliese,  the  edge  runner,  has  long  been  in  use  for  reducing  oil  seeds, 
fruit,  etc.,  to  meal  suitable  for  pressing.     As  employed  at  the  oil  mill,  the  edge  runner 


'thc    Engineer" 


V  Front     Elevation  /       \ 


Swain   Sc. 
Fig.  28.— ^<pecial  Grinding  Mill  with  Concave  Plates— Rose,  Downs  >S:  Thompson. 

differs  in  no  essential  respect  from  the  foim  used  in  many  other  industries.  Edge 
ninners  are  to  be  found  in  employment  in  chocolate  and  confectionery  factories,  for 
mixing  mortar,  m  paper  mills,  under  the  name  of  "kollei^angs,"  for  reducing  "broke" 


42        THE   PRODUCTION  AND  TREATMENT   OF   \T:GETABLE   OILS 

paper  to  pulp,  and  elsewhere.  An  oil  mill  edge  runner,  as  constructed  by  Robert 
Middleton  &  Co.,  of  Leeds,  is  illustrated  in  Fig.  27.  It  consists,  as  usual,  of  two  stones 
mounted  on  an  axle,  which  is  rotated  in  a  hoiizontal  plane  by  means  of  a  vertical 
shaft,  which  is  set  somewhat  nearer  one  of  the  stones  than  the  other.  In  the  case 
illustrated  the  stones  are  i  ft.  in  diameter  and  12  in.  wide.  The  driving  pulley  nuis 
at  about  100  revolutions  per  minute,  and  rotates  the  vertical  spmdie  through  bevel 
reduction  gearing  at  about  20  revolutions  per  minute.  The  action  of  the  rimner 
depends  as  usual  upon  the  sUpping  which  takes  place  between  the  edges  of  the  stones 


Fig.  29. — Eeducins  Mill  and  Cake  Breaker — Robert  Middleton. 


and  the  1  :cd  stone  on  which  they  run.  A  pair  of  sweepers  is  carried  romid  with  the 
vertical  shaft.'  These  sweepers  can  be  adjusted  to  guide  the  material  beneath  the 
stones  or  to  turn  it  outwards  so  as  to  discharge  it  through  an  outlet  door  in  the  pan 
sun-ounding  the  bed  stone.  In  the  case  of  machines  intended  for  reducing  linseed,  etc., 
the  runners  are  commonly  made  of  selected  hard  grit  stone.  For  reducing  olives,  a 
common  apphcation  of  the  edge  runner,  they  are  usually  made  of  granite.  The  edge 
runner  illustrated  was  designed  to  deal  with  about  4  tons  of  oHves  per  day,  and  absorbs 
in  its  driving  about  8  h.p. 

Other  alternatives  to  the  ordinary  rolls  take  the  form  of  special  grinding  or  reducing 
miUs  and  disintegrators. 


SOME    SPECIAL    FORMS    OF    REDUCTION    MACHINERY 


43 


Grinding  and  Reducing  Mills. 
A  special  form  of  grinding  mill  suitable  among  other  things  for  finely  grinding 
palm  kernels  and  copra,  is  illustrated  in  Fig.  28.  This  machine  is  made  by  Rose, 
Dowiis  &  Thompson,  Ltd.,  of  Hull.  It  contams  two  pairs  of  finely  fluted  rollers, 
the  bearmgs  of  which  are  acted  upon  horizontally  by  springs  which  peimit  the  lollers 
to  "  give  and  take  "  with  the  feed.  The  material  is  fed  from  the  hopper  at  the  top 
to  the  openuig  between  the  first  pair  of  rolls,  and  thence  passes  through  an  intermediate 
hopper  to  the  second  pair  of  rolls.  The  special  feature  of  the  mill  lies  in  the  provision, 
beneath  one  of  the  first  pair  of  rolls  and  beneath  both  of  the  lower  pair,  of  concave 
plates  between  which  and  the  associated  roller  the  material  must  pass  before  it  proceeds 
farther  on  its  course.  The  position  of  the  upper  concave  plate  is  adjusted  by  means 
of  two  screwed  rods  provided  with  springs  and  hand  wheels.  The  two  lower  plates 
are  similarly  held  up  to  their  work  and  adjusted  by  means  of  weighted  levers.  The 
discharge  of  the  material  takes  place  simultaneously  from  each  side  of  the  lower  pair 


i 


p-/-4g 


Auto. Feed 
100  R  PM. 


"The    Engineer" 


2  6i H 


FUi.  30. — Ili^^integl•ator — Rose,  Downs  &  Thompson. 


Swain    Sc. 


of  rolls.  The  machine  illustrated  has  an  output  of  from  30  to  40  cwt.  of  palm  kernels 
or  copra  per  hour.  Its  belt  pulley  runs  at  300  revolutions  per  minute.  About  24  b.h.p. 
is  required  to  drive  it.     Its  I'olls  are  16  in.  long  and  12  in.  in  diameter. 

The  object  of  fitting  the  concave  plates  beneath  the  rolls  of  this  machine  is  clear. 
Each  concave  is  in  its  effect  equivalent  to  the  provision  of  an  additional  roll  or  pair 
of  lolls.  Thus,  in  the  case  of  the  machine  illustiated  in  Fig.  28,  the  material  is  reduced 
to  the  same  extent  <as  it  would  be  if  it  were  passed  between  four  pairs  of  ordinary  rolls 
without  concaves.  Although  the  power  consumed  may  not  be  less  to  any  extent 
worth  considering,  the  concave  arrangement  results  in  a  considerable  saving  in  the 
space  occupied  by  the  machine  and  economises  in  capital  expenditure  and  upkeep 
charges. 

Another  form  of  reducing  mill  with  concaves,  made  in  this  case  by  Robert 
Middleton  &  Co.,  Leeds,  is  sho\vn  in  Fig.  29.  This  mill  is  fitted  with  two  pairs  of 
toothed  rolls  built  up  of  plates  keyed  and  bolted  together  on  mild  steel  shafts.  The 
degree  to  which  the  teeth  of  each  pair  of  rolls  intermesh  is  adjustable  to  g'.ve  the 
required  fineness  to  the  mateiial  being  treated.  The  rolls  of  each  pair  run  at  differential 
speeds,  about  60  and  80  revolutions  per  minute,  so  that  the  action  is  partly  a  tearing 
and  partly  a  crushing  one.  In  addition,  the  difference  in  speeds  avoids  any  tendency 
of  the  rolls  to  become  clogged  with  the  material  being  reduced.  The  machine  is  made 
in  two  forms.     In  one,  the  lighter,  a  concave  plate,  hinged  and  adjustable,  is  fitted 


44       THE   PRODUCTIOX   -VXD  TREATHENT   OF  ^T:GETABLE   OILS 


Fig.  31.  -Disintegrator,  .^^hovriDg  Beater  Anns,  'Waved  Plat«s,  and  Bar  Screen. 

beneath  one  of  tlie  lower  pair  of  rolls.  Li  the  other  form,  intended  for  an  increased 
output,  three  concave  plates  are  provided.  The  machine  illustrated  is  capable  of 
grinding  a  ton  of  copra  per  day.  Its  driving  absorbs  about  5  h.p.  The  belt  pulley 
runs  at  25U  revolutions. 


SOME    SPECIAL   FORMS    OF   REDUCTION   MACHINERY  45 

Disintegrators. 

Quite  a  diffeient  type  of  reducing  machine  for  copra,  palm  kernels,  and  so  on, 
made  by  Rose,  Do\vns  &  Thompson,  Ltd.,  is  illustrated  m  Figs.  30  and  31.  This 
raacliine  is  known  as  a  disintegrator.  It  comprises  a  cii'cular  casing  within  which 
there  revolves  at  a  high  speed  a  disc  carrying  four  flat-bar  beater  arms.  Each  side 
of  the  case  interior  is  fitt?d  with  chilled  iron  segmental  liners  the  surface  of  which 
is  waved.  Three  similarly  waved  chilled  iron  liners  are  dispo.sed  round  the  top  half 
of  the  periphery  of  the  case,  while  the  lower  half  of  the  periphery  is  formed  by  a  bar 
screen  in  two  parts.  The  material  to  be  treated  is  fed  into  the  casing  fi"om  a  hopper, 
the  feed  being  sometimes,  as  in  Fig.  30,  assisted  by  a  power-driven  worm.  Falling 
on  to  the  extremity  of  the  beater  arms,  the  nirterial  is  thrown  violentlj^  against  the 
chilled  iron  waved  plates  or  against  the  .screen  until  it  is  reduced  by  the  blows  which 
it  thus  suffers  to  a  degree  of  fineness  sufficient  to  enable  it  to  pass  through  between 
the  bars  of  the  screen.  It  will  be  noticed  that  the  liner  and  screen  segments  are 
designed  to  be  easily  replaceable.  The  size  of  machine  illustrated  in  Fig.  30  has  an 
output  of  24  cwt.  of  copra  or  such  like  material  per  horn*.  The  beater  shaft  runs  at 
1,700  revolutions  per  minute.  Twenty-eight  brake  horse-power  is  absorbed  in  driving 
the  machine. 

Special  Uses  for  these  Machines. 

The  special  forms  of  reducing  machinery  described  in  this  chapter,  with  the 
exception  perhaps  of  the  rolls  illustrated  in  Fig.  26,  can  be  and  are  used  for  other 
purposes  than  that  of  reducing  vegetable  oil-bearing  substances  wholly  or  partially 
to  the  form  of  meal  suitable  for  presshig.  Thus  the  disintegrator  just  described  has 
been,  we  are  informed,  successfully  applied  to  the  reduction  of  over  250  different  kinds 
of  material  ranging  fcom  broken  crockery,  iron  turnings  and  wood  shavings  to  coal, 
shoddy,  cork  and  bones.  With  such  uses  we  are  not  here  concerned,  but  it  may  be 
noted  that,  even  in  the  oil  mill,  alternative  uses  for  the  machinery  described  are  found. 
For  example,  oil  cakes  from  which  it  is  desired  to  recover  a  "  second  expression  "  oil 
may  be  once  more  reduced  to  the  form  of  meal  by  means  of  the  reducing  mill  illustrated 
in  Fig.  29.  When  used  thus  as  a  cake  breaker,  this  machine  can  deal  with  about 
3  tons  of  material  psr  hour.  Again,  the  cakes  taken  from  the  press  nearly  always 
have  their  edges  well  saturated  with  oil,  for  it  is  next  to  impos.sible  to  ])jevent  some 
of  the  oil  from  lingering  behind  at  the  edges  of  the  cake.  Partly  to  improve  the 
appearance  of  the  cake,  but  chiefly  to  avoid  wasting  oil,  these  edges  are  trimmed  off 
in  special  machines.  The  material  thus  recovered  is  reduced  again  to  the  form  of 
meal  and  returned  to  the  kettle  for  mixture  with  fresh  meal.  A  suitable  nuichine 
for  reducing  the  oily  edge  parings  to  meal  is  the  edge  runner,  .shown  in  Fig.  27.  Finally, 
in  the  manufacture  of  compound  feeding  cakes — a  ])rocess  sometimes  carried  on  at 
the  oil  mill  and  sometimes  in  an  entirely  .separate  establishment  devoted  solely  to  the 
work — the  special  grinding  mill  shown  in  Fig.  28,  or  the  disintegrator,  Figs.  30  and  31, 
is  of  great  service.  The  term  ''  compoimd  cake  "  has  been  used  to  denote  a  re-formed 
feeding  cake  made  from  a  mixture  of  genuine  press  cake  and  of  extracted  meal,  that 
is  to  say,  of  the  meal  left  after  seed  has  been  extracted  with  chemical  solvents.  As 
commonly  use:l,  however — at  least  in  this  country — the  words  denote  a  re-formed 
cake,  made  from  pure  linseed,  cotton  seed  or  other  press  cake  and  one  or  more  other 
ingredients,  the  addition  of  which  is  regarded  as  increasing  the  food  value  of  the  pure 
cake.  Among  such  added  materials  may  be  mentioned  locust  beans,  rice,  jjeas,  sugar, 
ginger,  lentils,  salt,  etc.,  besides  other  press  cakes  such  as  cocoa-nut  or  palmnut  cake. 
For  reducing;  these  materials  to  the  required  degree  of  fineness  preparatory  to  adding 
them  to  the  pure  cake  material  tti(!  machines  mentioned  can  conveniently  be  employed. 


CHAPTER   YIl 
MEAL  KETTLES.  RECEIVING  PANS  AND  MOULDING  MACHINES 


We  have  now  described  the  special  preparatoiy  machineiy  in  use  for  the 
preliminary  treatment  of  certain  typical  oil-beaiing  vegetable  substances,  namely, 
copra,  linseed,  pahn  fruit,  palm  kernels,  cotton  seed  and  castor  seed.     The  material, 

whatever  its  original  form, is.  as  delivered 
from  the  preparatory  machinery  so  far 
described,  in  the  form  of  "  meal."  The 
next  step  in  the  process  is  to  heat  this 
meal — if.  that  is  to  say,  the  oil  is,  as  it 
more  usually  is  than  not,  to  be  expressed 
hot.  The  heating  of  the  meal  is  com- 
monly conducted  in  a  steam  "  kettle," 
and  is.  of  course,  carried  out  immediately 
before  the  pre-sing  takes  place,  so  Ihat 
the  material  when  placed  in  the  press 
may  still  be  liot. 

The  heating  of  the  meal  greatly 
facilitates  the  expression  of  the  oil  from 
it.  for  it  resiUts  in  the  rupturing  of  the 
minute  vessels  or  sacs  in  which  the  oil 
is  naturally  contained  within  the  meal. 
In  so  far  as  it  does  this  it  directlj- reheves 
the  press  of  a  corresponding  amount  of 
work.  In  addition,  the  heating  of  the 
meal  naturally  reduces  the  viscosity  of 
tiic  oil,  and  therefore  renders  its  flow 
easier.  A  third  effect  of  heating  is  also 
to  be  noted.  Any  albuminous  matter 
present  in  the  meal  will  be  coagulated 
or  solidified  during  the  heating  process, 
and  will  thereby  be  largelj'  retained 
within  the  cake  left  in  the  press  and 
wjll  not  flow  away  with  the  oil.  The 
heating  proper  of  the  meal  is  effected 
usually  by  means  of  a  steam  jacket 
surrounding  the  kettle.  Frequently,  it  will  be  found  that  a  little  steam  is,  in  addition, 
admitted  direct  to  the  meal  when  in  the  kettle.  The  object  of  this,  however,  is  not 
so  much  to  heat  the  meal  as  to  "  temper  "  it  so  as  further  to  facilitate  the  flow 
of  oil. 

The  meal  is  withdrawn  from  the  kettle  in  convenient  amounts,  and  is  immediately 
rough-moulded  in  a  machine  into  rectangular  or  other  shaped  slabs  or  cakes  of  a  size 
suitable  for  the  press  in  use.     As  quickly  as  made  these  cakes  are  taken  to  the  press, 


Fig.  32.— Meal  Kettle— Manlove,  AUiott 


MEAL  KEITLES,   RECEIVING  PANS    AND  MOULDING  MACHINES       47 


so  that  they  may  be  pressed  before  they  lose  their  heat.     The  cakes,  after  pressing, 
are,  of  eourse,  those  known  to  farmers.     They  are  very  commonly  either  oblong  or 
oval,  and,  as  trimmed,  vary  in  size  from 
about   21  in.  to  2G  in.  long  by  11  in.  to 
13  in.  wide. 

Meal  Kettles. 

A  typical  meal-heating  kettle,  made  Ijy 
Manlove,  Alliott  &  Co.,  Ltd.,  of  Notting- 
ham, is  illustrated  in  Fig.  32.  The  kettle 
is  a  cjiiudrical  iron  vessel  jacketed  round 
its  side  and  bottom  for  heating  steam  at 
a  pressure  of  about  75  lb.  and  containing 
power-driven  stiri'ing  gear.  The  steam 
jacket  round  the  side  is  covered  with  a 
layer  of  non-conductin;j;  material,  enclosed 
within  a  sheet  metal  casing.  The  top  of 
the  kettle  is  open,  except  for  the  cast-iron 
bridge  which  spans  it  and  carries  the 
dri\'ing  gear.  The  bottom  of  the  kettle 
with  its  steam  jacket  is  made  readily 
detachable  from  the  rest  for  renewal 
purposes,  as  this  part  is  that  which  is 
most  subjected  to  wear.  The  thorough 
agitation  of  the  meal  in  the  kettle  is 
necessary,  not  only  to  attain  uniform 
heating,  but  also  to  prevent  it  becoming 
discoloured. 

A  feature  of  the  apparatus  illustrated 
in  Fig.  32  lies  in  the  fact  that  the  vertical 
agitator  shaft  is  carried  through  the 
bottom  of  the  kettle  and  is  supported  on 
'an  external  ball  thrust  bearing.  This 
considerably  reduces  the  power  rccpiired 
to  drive  the  agitator.  It  will  be  noticed 
that  a  perforated  box  surrounds  the 
agitator  shaft  where  it  passes  through 
the  kettle  bottom.  This  is  for  the 
admission  of  saturated  steam  to  the  mass 
in  the  kettle.  The  admission  of  such 
steam  results  in  the  moistening  or  '  tem- 
pering "  of  the  meal,  and  facilitates  the 
subsequent  flow  of  oil  from  it.  The  means 
provided  for  withdra\\ing  a  charge  of 
meal   from   the   kettle   and   delivering  it 

to  the  preliminary  cake  moulding  machine  can  be  gathered  from  Figs.  32  and  33.  At 
the  foot  of  the  kettle,  an  orifice,  opened  and  closed  by  a  shutter,  is  formed.  Beneath 
this,  a  flat  board  is  hung  whereon  a  strickling  box — see  Fig.  33 — open  at  the  top  and 
bottom,  can  be  run.  The  shutter  is  arranged  to  be  automatically  opened  when  the 
strickling  box  is  pushed  beneath  it,  and.  closed  when  it  is  withdrawn.     The  strickling 


Fig.  33.— Double  Kettle— Manlove,  Alliutt. 


48 


THE  PRODFCnOX  AXD  TREATMENT  OF  VEGETABLE  OILS 


box  with  its  charge  is  ptiUed  on  to  the  table  of  the  moiUdiiig  machine — see  Fig.  34. 
The  a^tator  shaft  carries  at  its  foot  a  pair  of  arms,  which  help  to  pass  the  me^  from 
the  kettle  through  the  orifice  into  the  strickling  box. 

These  kettles  are  made  in  various  sizes,  ranging,  sav.  from  1  ft.  8  in.  diameter 
by  1  ft.  3  in.  deep  to  6  ft.  diameter  by  2  ft..  8  in.  deep.  In  some  instances,  two  are 
arranged,  one  on  top  of  the  other.  Such  a  pair,  made  by  Messrs.  ManloTe,  Alliott, 
is  shown  in  Fig.  33.  This  arrangement  not  only  simplifies  the  driving  gear  required, 
but  also  facilitates  the  working  and  ensures  that  the  meal  delivered  to  the  presses 


Fig.  34. — Kettle  and  Moulding  1^ 

shall  b?  at  an  even  temperature.  Both  kettles  are  steam  jacketed.  The  uppK  one 
receives  the  meal  in  the  first  instance.  Having  been  heated  to  a  certain  degree,  the 
meal  is  discharged  from  the  upper  to  the  lower  kettle  throogh  a  s!ide  in  the  bottom 
of  the  former.  When  heated,  ready  for  the  press,  it  is  withdrawn  from  the  latter  in 
the  usual  way.     Both  kettles  contain  agitating  gear. 

The  engraving  Fig.  34  shows  a  meal-heating  kettle  and  moulding  machine  made 
by  Robert  Middleton  &  Co.,  Leeds.  The  view  is  htxe  given,  as  it  ^on^  veiy  dearij 
the  relative  situations  in  use  of  the  kettle  and  the  moulding  machine.  The  driving 
pulley  of  this  kettle  rmis  at  about  130  revoluti<ms  and  the  a^tator  shaft  at  about 
30  revolutions.     Some  3  h.p.  or  so  is  consumed  in  driving  it. 


MEAL  KETTLES,  RECEIVING  PANS  AND  I\IOULDING  MACHINES        49 

Receiving  Pans. 

When  tlic  meal  is  to  be  pressed  cold  a  heating  kettle  is,  of  course,  not  required. 
It  is  convenient,  however,  to  provide  a  "  recei^ng  pan  "  for  the  meal,  from  which 
the  moulding  machines  may  draw  their  supply.    The  kettle  itself  acts  as  such  a  receiving 


26  dia.  Pulley 


%J^Se<f 


The  Engineer" 
Fig.  :\b 


-Receiving  Pan  and  Moulding  Machines — Manlove,  Allioft. 


pan  when  hot  pressing  is  being  followed,  and  with  the  steam  shut  off  from  the  jackets 
may  still  so  serve  when  cold  pres.sing  is  adopted.  If  cold  pressing  is,  however,  the 
rule  rather  than  the  exception,  it  is  clearly  not  desirable  to  spend  money  on  a  kettle 
when  a  simpler,  cheaper  receptacle  will  serve  the  purpose  equally  well.     The  arrange- 


50         THE   PRODUCTION   AND  TREATilENT   OF   \^GETABLE   OILS 

ment  of  a  5  ft.  6  in.  receiving  pan,  by  Manlove,  Alliott  &  Co.,  Ltd.,  is  given  in  Fig.  35. 
This  pan  may  be  described  as  a  kettle  without  the  steam  jackets  and  other  heating 
adjuncts.  It  contains  a  modified  foi-m  of  stirring  gear,  the  purpose  of  which  is  simply 
to  ensure  proper  delivery  of  the  meal  to  the  outlets  at  the  foot  of  the  vessel.  There 
are  two  .such  outlets  in  tliis  example,  each  controlled  by  an  independent  shutter  and 
meal  box.  and  each  serving  a  sejjarate  moulding  macliine. 

Meal-Mouldixg  Machines. 

AVe  now  pass  on  to  describe  the  construction  and  working  of  the  meal-moulding 
machines.  The  object  of  these  machines  is  to  press  the  meal  into  the  form  of  a  cake, 
so  as  to  facilitate  the  filling  of  the  main  presses.  The  moukhng  pressure  employed 
must  not  exceed  that  at  which  oil  will  commence  to  flow  from  the  meal.  The  nearer 
it  approaches  this  amount,  however,  the  less  will  be  the  work  required  subsequently 
of  the  main  press;  while  the  greater  the  preliminarj^  compression  of  the  meal  in  the 
moulding  machine,  the  less  will  be  the  height  of  the  main  press  required  for  a  given 
output.  The  moulding  machine  must  be  reliable  and  quick  in  its  action.  As  each 
cake  is  formed  in  it,  the  cake  is  taken  away  to  the  press  and  a  succeeding  cake  moulded. 
The  pr^ss  may  hold  sixteen  or  more  cakes,  and  not  till  these  cakes  are  all  in  place  can 
the  pressing  be  commenced.  The  moulding  machine  must  work  regularly  and  quickly, 
for  it  is  not  desirable  to  have  a  considerable  difference  in  the  temperatures  of  the  fii'st 
and  last  cakes  placed  in  the  press.  Where  cold  pressing  is  in  force,  the  moulding 
machine  can,  of  course,  be  worked  more  leisurely  than  is  desirable  with  hot  meal. 

Moulding  machines  are  obtainable  in  various  forms.  In  general,  they  are  operated 
by  hydraulic  pressure  taken  from  the  accumulators — the  low-jiressm'e  accumulator, 
if  there  be  such — provided  for  the  working  of  the  main  presses.  They  are  sometimes 
designed  to  be  operated  bj'  hand,  the  necessary  force  being  apphed  through  a  screw. 
OccasionaUj^  they  are  worked  by  steam  pressure. 

A  hydraulic  moulding  machine  of  a  usual  t^'pe,  made  by  Manlove,  Alliott  &  Co., 
Ltd.,  is  illustrated  in  Fig.  36.  As  will  have  been  gathered  already,  the  moulding 
machine  is  placed  close  beside  the  kettle  so  that  the  strickling  box  filled  with  meal 
may  be  readily  drawn  over  on  to  it.  Li  the  case  of  the  machine  showTi  in  Fig.  36, 
the  kettle  would  be  arranged  on  the  right-hand  side. 

The  strickling  box  leaving  the  supporting  board  of  the  kettle  passes  on  to  the 
hard-wood  block  or  frame  shown  at  the  front  of  the  machine,  being  guided  thereon 
by  the  upstanding  edges  of  the  block.  The  block  is  counterbalanced  and  is  liinged 
to  turn  upwards  and  backwards.  In  the  view  given  it  is  resting  upon  a  sliding  table, 
which  for  the  time  being  is  in  its  extreme  forward  position.  Before  the  strickling 
box  is  pulled  across,  the  wood  block  is  lifted  up  and  a  tray  of  sheet  steel  is  placed  on 
top  of  the  sliding  table.  Over  this  tray  is  placed  a  length  of  "  press  bagging,"  a  woven 
material,  the  nature  and  function  of  which  will  be  explained  in  due  course.  The 
wood  block  is  then  lowered  back  on  to  the  sliding  table  and  the  strickling  box  run  out 
so  as  to  fill  the  hole  in  the  block  with  meal.  On  hinging  back  the  wood  block,  a  gauged 
amount  of  meal  is  thus  left  standing  on  the  tray  and  press  bagging.  The  bagging  is 
of  the  same  width  as  the  cake  to  be  formed,  and  of  about  twice  the  length.  The  two 
ends  are  folded  over  the  top  of  the  meal,  and  the  sliding  table,  with  the  tray,  bagging 
and  meal,  is  pushed  forward  over  the  hydraulic  ram.  The  sliding  table  .supports  the 
tray  round  three  of  its  edges.  When  the  table  is  pushed  over,  it  moves  a  lever  operating 
the  valve  of  the  hydraulic  ram.  so  causing  the  head  of  the  latter  to  rise  against  the 
underside  of  the  tray,  lift  it  off  the  table,  and  compress  the  meal  agamst  the  fixed 
head  of  the  machine.     The  table  meanwhile  is  withdrawn  and  made  ready  for  moulding 


MEAL  KETTLES,  RECEIVING  PANS  AND  MOULDING  MACHINES      51 


Fig.  ;i6. — Ordiuary  Form  of  Hydraulic  Moulding  Machine — Mnnlove,  Alliott. 


Fig.  37. — Special  Fonn  of  Hydraulic  Moulding  Machine — Manluve,  Alliott. 

a  second  cake.  The  ram  is  lowered  by  operating  tlie  valve  lever  by  hand,  and  the 
cake  and  bagging  supported  on  the  tray  are  removed  to  the  presses.  The  pressui'e 
employed  in  the  hydraulic  cylinder  is  from  500  lb.  to  GOO  lb.  per  square  inch. 

The  above  form  of  machine  is  thought  by  some  to  suffer  from  a  disadvantage 


52         THE  PRODUCTION   AND   TREATMENT   OF   VEGETABLE   OILS 

iu  that  the  meal  during  the  swmging  up  of  the  wood  block,  and  during  the  movement 
forward  on  to  the  ram,  is  liable  to  be  shaken  with  the  consequent  production  of  a 
misformed  cake.  A  moulding  machine  designed  to  overcome  this  objection,  made 
by  Messrs.  Manlove,  AUiott,  is  shown  in  Fig.  37  and  also  in  Fig.  35.  In  this  case, 
the  head  of  the  machine  is  hinged  so  that  it  may  be  swung  over  and  thus  permit  the 
meal  to  be  moulded  while  still  supported  round  the  four  edges  by  the  wooden  frame 
or  block.  The  tray  and  bagging  are  placed  directly  on  top  of  the  ram  head,  the  wood 
frame  is  swung  down  and  the  strickling  box  is  advanced  to  fill  the  frame  with  meal. 
The  frame  is  then  lifted  up  and  again  lowered  after  the  ends  of  the  bagging  have  been 
turned  over.  The  head  is  thereafter  lowered  so  as  to  enter  the  hole  in  the  wood  frame, 
and  is  locked  in  this  position  by  means  of  the  spring  rod  shown  at  the  front  of  the 
machine  in  Fig.  37.  Pressure  is  then  applied  within  the  hydraulic  cylinder  to  compress 
the  tray,  bagg'ng  and  meal  agamst  the  machine  head.  The  wooden  frame  be'ng 
pivoted,  lifts  slightly  while  this  is  occurring. 

Automatic  Moulding  Machines. 
Quick,  easy  operation  being  very  desirable  in  a  meal-moulding  machine,  it  is 
natural  to  find  that  efforts  have  been  directed  towards    making    the  action  more 
automatic  than  it  is  in  the  machines  of  the  type  described  above. 

An  automatic — more  correctly  a  semi-automatic — meal-moulding  machine,  made 
by  Rose,  Downs  &  Thompson,  Ltd.,  is  illustrated  in  Figs.  38  and  38a.  This 
macliine  consists  of  two  moving  parts,  namely  a  horizontally  sliding  measuring  box  A 
and  a  vertically  sliding  moulding  box  B.  The  movement  of  the  boxes  is  effected 
hydraulically,  and  is  controlled  from  the  handles  C  and  D  respectively.  E  indicates 
the  lower  face  of  the  heating  kettle.  The  ends  of  the  moulding  box  B  are  open,  so 
that  the  usual  tray  and  bagging  may  be  slipped  into  the  box.  With  these  in 
position,  the  measuiing  box  A  is  moved  into  its  extreme  left-hard  jiosition  and  a 
charge  of  meal  is  withdrawii  from  the  kettle  and  is  gathered  into  the  hole  F  in  the 
box.  The  measuring  box  is  then  moved  over  to  the  right.  Any  surplus  meal 
standing  more  than  -^  in.  abov^e  the  level  of  th?  top  of  the  mea.suring  box  is  swept  off 
by  the  edge  of  the  oblong  boss  C4  on  the  entablature  H.  Such  surplus  meal  is  carried 
back  on  to  the  plain  rear  portion  of  the  measuring  box,  and  thence  can  be  swept 
into  the  hole  F  on  the  next  stroke.  The  meal  in  the  hole  F,  as  the  measuring  box 
advances,  falls  into  the  moulding  box,  where  it  rests  on  top  of  the  tray  and  bagging 
already  there.  The  measuring  box  is  now  returned  to  its  extreme  left-hand  position, 
the  bagging  is  folded  over  and  the  moulding  box  is  raised  so  as  to  compress  the 
meal  against  the  boss  G.  Care,  as  we  have  already  said,  is  required  to  see  that  the 
pressing  is  not  carried  so  far  that  oil  will  be  forced  from  the  meal.  This  effect  is 
secured  in  this  machine  by  limiting  the  upward  movement  of  the  moulding  box  by 
means  of  the  nuts  and  washers  on  the  ends  of  two  rods  J  attached  to  it. 

The  machine  is  semi-automatic  in  so  far  as  the  movement  of  the  measuring  box 
is  concerned.  The  right-hand  end  of  the  hydraulic  cylinder  operating  this  box  is 
constantly  open  to  hydraulic  pressure  through  the  pipe  K.  By  reason  of  the  presence 
of  the  piston-rod,  the  working  area  on  this  side  of  the  piston  is  less  than  it  is  on  the 
other.  Hence,  if  the  same  hydraulic  pressure  is  admitted  to  both  sides  of  the  piston, 
the  measuring  box  will  be  moved  to  the  right.  Wien  the  box  approaches  its  extreme 
right-hand  position,  a  gudgeon  L  attached  to  it  strikes  the  end  of  a  lever  M  coupled 
up  M'ith  the  handle  C  and  the  valve  N  Avhich  this  handle  controls.  The  left-hand  end 
of  the  hydraulic  cyhnder  is  thus  set  to  exhaust,  and  the  measuring  box  automatically 
moves  back  again  to  the  left.     The  moulding  box  must  not,  of  course,  be  raised  mitil 


MEAL  KETTLES,  RECEIVING  PANS    AND  MOULDING  MACHINES      53 

the  measuring  box  is  fully  out  of  the  way.     To  prevent  accidents,  the  end  of  the  rod 
on  which  the  handle  D  is  fixed  is  formed  with  a  cam  incline  on  which  the  roller  of   a 


f*^*^4^^^ 


'(y^-^dF^ 


-— — 


VtBndlc  Far  Controlling 
'I    ,  Measuring  ffon  fiam. 

Swain  Sc. 
Fig.  38. — Semi-Autom  itic  Moulding  Machine — Rose,  Downs  &  Thompson  (for  front  elevation 

see  Fig.  ;jSa). 

l)lungcr  P  operates.  To  fit  the  toj)  end  of  this  jjlunger  a  hole  is  formed  at  Q  on  the 
underside  of  the  measuring  box.  The  handle  D  cannot  thus  be  moved  until  the 
measuring  box  occupies  its  extreme  left-hand  ]iosition. 

The  maclijnc  illustrated  is  caijable  of  rough-moulding  the  meal  to  meet  the  require- 


54         THE   PRODUCTION   AND  TREATMENT   OF   ^'EGETABLE   OILS 

ments  of  eight  16-cake  presses.  It  is  worked  from  the  low-pressure  accumulator 
installed  for  the  presses  or  by  any  other  source  of  hydraulic  power  at  a  pressure  of 
about  700  lb.  per  square  inch.  The  facts  that  its  action  is  automatic  to  the  extent 
indicated,  and  that  ii:  disjjenses  with  the  use  of  a  hinged  wood  frame,  make  it,  it  is 
claimed,  especially  suitable  for  installation  where  labour  is  unskilled  and  result  in 
its  capacity  being  twice  that  of  a  corresponding  moulding  machine  of  the  ordinary 
pattern. 

Press  Bagging. 

We  have  refeiTed  above  to  the  "  press  bagging,"  in  which  the  cakes  as  moulded 
are  wrapped  befoie  being  placed  in  the  press.     The  trays  used  during  the  moulding 


^^^€^=^^^^m^-^-^^^\^ 


Fig.  38a. — Semi-Automatic  Muiilding  Machine — Eose,  Downs    & 
Thompson. 

operation  are  i?imply  for  supporting  the  formed  cake  while  it  is  being  carried  to  and 
placed  in  the  press.  They  arc  not  insertel  in  the  press  with  the  cake.  The  bagging, 
on  the  other  hand,  is  .so  inserted,  and  is  not  strip])ed  from  the  cake  until  the  pressing 
is  completed.  This  bagging  is  made  of  wool,  camel-hair,  or  alpaca,  the  first-named 
being  the  generally  prefeiTed  material.  It  is  commonly  obtainable  in  different  widths, 
varying  from  10  in.  to  131  in.  and  weighing  respectively  12\  oz.  to  17  oz.  per  yard 
run.  It  is  not  simply  a  wrapping  for  the  cake.  It  fulfils  in  reality  a  most  important 
function,  for  without  its  presence  the  yield  of  oil  from  the  meal  would  be  considerably 
reduced.  Were  its  use  discarded,  the  flow  of  oil  from  the  meal  would  cease  as  soon 
as  the  applied  pressure  con-;ol:'dated  the  meal  and  closed  up  the  interstices  through 
which  the  first  portion  of  the  oil  might  run.  The  oil  would,  in  fact,  have  to  travel 
anything  up  to  half  the  length  of  the  cake  through  the  meal  itself.     With  the  bagging 


JIEAL  KETTLES,  RECEIVING  PANS  AND  MOULDING  MACHINES        55 

in  use  an  easy  passage  outwards  is  provided  for  the  oil.  The  oil,  in  order  to  reach  the 
bagging,  does  not  require  to  travel  through  the  meal  for  a  greater  distance  than  halt 
the  Ihickness  of  the  cake. 

The  expression  "  bagging  "'  arose  fi'om  the  fact  that  formerly,  before  moulding 
machines  were  introduced,  the  meal  was  filled  into  actual  bags  which  were  placed 
without  further  work  into  the  press.  This  method  of  working  suffered  from  all  the 
disadvantages  which  the  preliminary  formation  of  a  partially  compressed  cake  of 
even  thickness  and  uniform  size  is  intended  to  overcome.  The  method  is  still 
occasionally  employed,  notably  in  the  case  of  manually  operated  presses  and  in  other 
small  installations  specially  intended  for  export  to  oil -seed-producing  areas. 


CHAPTER   VIII 

OIL  PRESSES— ANGLO-AMERICAN  TYPE 

As  we  explained  in  Chapter  I.,  vegetable  oils  are  extracted  from  the  properly 
prepared  oil-beaiing  substances  in  either  of  two  ways,  one  being  by  the  application 
of  pressure,  and  the  other  being  by  the  use  of  chemical  solvents.  With  the  latter 
method  we  shall  deal  in  a  succeeding  chapter.  The  former,  the  pressure  method, 
and  the  machinery  required  for  it,  will  be  dealt  with  first,  as  it  is  i  ndoubtedly  true 
that,  for  the  present,  more  oil  is  recovered  by  it  than  bj^  the  chemical  solvent  method. 

Development  of  the  Oil  Press. 

A  word  may  perhaps  be  said  as  to  the  historical  development  of  the  oil  press. 
The  ancients  used  presses  operated  by  wedges  or  levers.  The  Greeks  and  Romans, 
in  the  recover}'  of  olive  oil,  employed  screw  presses,  which  followed  closely  in  design 
the  usual  form  of  wine  press.  The  screw  type  of  press  persisted  in  use  for  many 
centuries,  and  may  still  be  said  to  be  in  employment  in  the  shape  of  certain  small 
hand-power  presses  having  a  capacity  of  8  lb.  to  10  lb.  of  seed  per  charge,  and  supplied 
for  trial  and  other  purposes.  In  the  seventeenth  century  the  Dutch  "  stamper  " 
press  was  invented.  Although  in  principle  it  was  but  a  revival  of  the  wedge  press 
of  the  ancients,  it  played  an  important  part  in  the  development  of  the  industiy.  per- 
sisting in  use  even  some  considerable  time  after  the  development  and  application 
of  the  hydraulic  press.  The  Dutch  press  consisted  of  an  oblong  wooden  or  cast-iron 
box  containing  a  perforated  double  bottom.  A  bag  filled  with  meal  was  placed  at 
each  end  of  the  box,  between  perforated  iron  plates.  The  space  between  the  two 
bags  was  filled  up  with  wooden  blocks  and  wedges.  Over  the  box  was  erected  a 
framework  on  which  was  swung  a  balk  of  timber  some  16  ft.  long  by  8  in.  or  so  square. 
This  balk  was  lifted  and  allowed  to  fall  on  one  of  the  wedges  in  the  box  by  means  of 
a  revolving  slaft.  Al)out  fifteen  blows  a  minute  were  delivered  on  to  the  wedge, 
the  height  of  fall  of  the  balk  being  about  2  ft.  A  blow  delivered  on  a  second  and 
inverted  wedge  loosened  the  blocks  and  bags  in  the  box  when  the  pressing  was 
completed. 

The  development  by  Braniah  of  the  hydraulic  press  received  application  in  the 
oil-seed-cru.shing  industiy  early  in  the  nineteenth  century.  The  first  hydraulic  oil 
presses  were  little  more  than  Dutch  presses  in  which  hydraulic  power  was  substituted 
for  that  obtained  from  wedges  and  a  falling  weight.  Horizontal  oil  presses  continued 
in  use  for  some  considerable  time,  but  the  economy  of  floor  jpace  and  other  advantages 
attendant  upon  a  vertical  position  were  early  recognised,  and  development  followed 
in  that  direction.  The  earlier  vertical  prcs:es  were  designed  to  deal  with  the  oil  meal 
in  bags,  just  as  in  the  case  of  the  Dutch  press.  The  presses  were  provided  with  two 
tubs  or  circular  boxes  of  metal,  one,  perforated  aU  over,  being  placed  witliin  the  other, 
which  was  used  to  catch  the  expressed  oil.  The  bags  of  meal,  with  a  metal  jilate 
between  each,  were  deposited  \\itliin  the  inner,  perforated  box,  and  the  whole,  resting 
on  the  head  of  the  hydraulic  ram,  was  forced  upwards  against  the  overhead  entablature 
of  the  press,  a  circular  boss  on  the  underside  of  which  entered  the  perforated  box  and 


INSERT  FOLDOUT  HERE 


OIL    PRESSES— ANGLO-AMERICAN    TYPE  57 

exercised  the  necessary  reaction  on  the  meal  bags.  It  was  soon  found  that  this  method 
of  worliing  could  be  improved  upon  if  each  bag  of  meal  were  pressed  in  a  separate  box, 
and  as  a  result  the  "  box  press,"  with  four  or  so  separate  seed  boxes,  came  into  favour. 

Modern  Hydraulic  Presses. 

Up  to  this  point  it  was  universally  the  custom  to  press  the  meal  in  bags.  These 
bags  were  a  source  of  trouble  and  expense,  for  they  were  readily  damaged,  and  had 
constantly  to  be  renewed.  Their  employment,  however,  was  dictated  largely  by  the 
convenience  which  they  provided  in  charging  the  press  with  meal.  With  the  develop- 
ment of  the  meal-moulding  or  forming  machine  a  new  direction  was  given  to  the 
evolution  of  the  oil  press.  The  moulding  machine  permitted  the  meal  to  be  handled 
and  placed  in  the  press  without  the  use  of  bags.  The  cakes,  rough  formed,  had  only 
to  be  wrai:)ped  in  press  cloths  and  taken  to  the  press  on  a  tray.  We  have  already 
explained  that  the  function  of  the  press  cloths  is,  not  only  to  provide  a  filtering  medium, 
but  also  to  establish  a  passage  oiitwards  for  the  oil  when  the  meal  closes  up  under 
pressure.  This  function  was,  of  course,  also  fulfilled  by  the  old-fashioned  bags,  but 
in  contrast  with  these  the  i:)ress  cloths  are  far  less  readily  damaged,  and  can  be  renewed 
simply  by  cutting  off  lengths  from  a  roll  of  cloth.  With  this  development,  boxes  were 
no  longer  required  in  the  press,  and  were  replaced  by  a  series  of  horizontal  plates, 
between  wliich  the  rough-formed  cakes  could  be  placed  and  pressed.  This  system  of 
press,  the  Anglo-American,  as  it  is  universally  called,  was  introduced  into  this  country 
in  1873  by  Rose,  Downs  &  Thompson,  Ltd.,  of  Hull,  and  was  at  first  applied  only 
to  the  crushing  of  linseed  and  similar  small  oil-bearing  seeds.  To-day  il  is  in  extensive 
employment  for  extracting  oil  from  many  kinds  of  seeds,  nuts,  etc.  In  a  common 
size  it  is  i^rovided  with  i^lates  sufficient  to  make  sixteen  cakes  at  one  pressing,  repre- 
senting a  total  charge  of,  sayj  320  lb.  of  crushed  seed. 

In  a  .still  later  type  of  oil  press,  laiown  as  the  "  cage  press,"  something  of  a  reversion 
to  the  earliest  form  of  box  press  is  to  be  observed.  The  cage  press  derives  its  name 
from  the  fact  that,  in  place  of  the  horizontal  plates  of  the  Anglo-American  system, 
there  is  substituted  a  circular-sectioned  cage  built  up  of  finely  spaced  upright  bars. 
Inside  this  cage  the  meal  is  placed  in  layers  separated  from  one  another  by  means  of 
press  cloths  and  discs  of  metal.  The  cakes  turned  out  by  this  form  of  press  are  circular. 
The  system  has  recently  come  into  extensive  use,  and  is  particularly  adapted  for 
pressing  castor  seed,  copra  and  other  substances  of  a  very  oily  nature,  which  are 
commonly  pressed  twice.  The.se  two  tj^jcs  of  press,  the  Anglo-American  and  the  cage, 
at  present  hold  the  field.  Typical  examples  of  each  will  now  be  described  and 
illustrated. 

Typical  Anglo-American  Presses. 

In  Plate  I.  we  reproduce  a  drawing — kindly  prepared  for  us  by  Manlove,  Alliott 
&  Co.,  Ltd.,  of  Nottingham— showing  an  Anglo-American  oil  jjress  and  some  of  its 
details.  This  example  consists  of  a  cast-iron  head  and  bottom,  united  by  four  forged 
steel  columns  having  l)uttrcss-thieaded  nuts  at  each  end,  a  cast  .steel  cylinder  resting 
within  the  bottom  casting,  and  a  hollow  cast  iron  ram  supporting  a  cast-iron  table  or 
head.  The  bottom  ca.sting  is  flanged  all  round  to  form  a  tray  in  wliich  the  expressed 
oil  is  caught.  Between  the  top  and  bottom  castings  fifteen  steel  press  plates  are 
arranged  horizontally.  These  ])lates  provide  spaces  for  sixteen  cakes,  each  .space, 
when  the  plates  are  fully  dropped,  being  2i  in.  in  depth.  Each  plate  is  hung  from  the 
one  above  by  means  of  four  oval  mild  steel  links  slijjpcd  over  square-headed  studs 
screwed  into  the  plate  edges,  the  topmost  plate  of  all  being  hung  similarly  from  the 


58 


THE  PRODrmox  Axr>  TREA'nrENT  OF  ^t:getable  oils 


top  casting.  To  the  inner  side  of  each  of  the  four  columns  of  the  press  a  flat,  square- 
edged  runner  or  giiide  is  pinned.  The  width  of  the  plates  is  a  loose  fit  between  these 
guides,  while  sqtiare-headed  studs,  screwed  into  the  jjlate  edges,  engage  the  outer 
faces  of  the  guides,  and  prevent  the  plates  moving  length^vise.  This  method  of 
supporting  the  plates  secures  the  required  condition,  namely,  that  the  plates,  when 


Fig.  oH. — Batterv  ul  iinu  .lUtrn-.^Uiencan  i'resse? — ManloTe,  Alliott. 

pressed  upwards,  should  close  together  without  friction,  or  at  least  without  cumulatiTe 
frictional  resistance.  Were  this  condition  seriously  departed  from  there  would  be  a 
danger  of  the  upper  cakes  Ijeing  less  thoroughly  pressed  than  the  lower. 

The  press  plates  are  corrugated  in  the  manner  shown  in  the  engraving.  These 
corrugations,  as  well  as  the  longitudinal  ridges  which  are  raised  on  the  plate,  are 
intended,  as  far  as  possible,  to  prevent  the  meal  from  spreading  when  the  pressure  is 
applied.     If  a  brand  mark  is  required  on  the  finished  cake  the  desired  letters,  etc.,  are 


OIL    PRESSES— ANGLO-AMERICAN   TYPE 


59 


raised  or  sunk  on  one  side  of  each  press  plate.  The  press  plates  are,  in  the  instance 
illustrated,  of  steel.  They  are  frequently  rolled  to  the  required  formation. 
Occasionall\-  they  are  built  up  from  steel  plates.  When  a  brand  mark  is  required 
on  them  they  are  commonly  made  of  malleable  cast  iron.  The  same  presses  may  not, 
however,  always  be  used  for  one  class  or  quality  of  material.  Under  these 
circumstances,  to  avoid  having  to  change  the  i)lates  to  obtain  merely  a  different 
brand  mark,  plates  are  made  in  which  the  brand  mark  is  formed  on  a  removable 
portion. 

The  ram  of  the  press  illustrated  in  Plate  I.  is  16  in.  in  diameter.  The  working 
pressure  is  2  tons  per  square  inch,  so  that  the  total  force  exerted  is  some  400  tons. 
This  gives  about  §  ton  per  square  inch 
a.s  the  pressui'e  exerted  on  the  meal 
cake.  The  hydraulic  pressure  is  some- 
times transmitted  to  the  ram  cylinder 
by  means  of  water  alone,  or  of  water 
mixed  with  glycerine,  to  prevent  the 
liquid  from  freezing  too  readily.  Fre- 
quently, however,  the  working  fluid 
preferred  is  oil,  and,  if  possible,  oil  of 
the  same  nature  as  tliat  being  extracted, 
the  reason  being  that  any  leakage  of  tiie 
working  fluid  from  the  cylinder  into 
the  tray  catching  the  expressed  oil  is 
thus  rendered  harmless  in  its  effect 
upon  the  oil  being  recovered. 

Anglo-American  presses  are  usually 
arranged  in  oil  mills  in  sets  of  four,  as 
shown  in  Fig.  39,  where  a  battery, 
made  by  Messrs.  Manlove,  Afliott,  is 
illustrated.  The  fourth  press  in  this 
vie^  is  represented  without  its  plates. 
The  presses  are  eni  irely  separate.  Some- 
times, however,  they  are  to  be  found 
provided  with  a  common  gutter  or 
tray  for  catching  the  oil.  They  are 
worked  separately  but  in  unison.  Thus,  while  one  press  is  being  charged 
another  is  having  the  pressure  applied  to  it,  a  third  is  standing  under  the 
pressure,  and  the  fourth  is  l)eing  unloaded.  The  pres.ses  illustrated  in  Fig.  39 
are  of  the  same  size  and  general  design  as  that  repiescnted  in  Plate  I.  One 
secondary  point  of  difference  is  to  be  noticed  in  tiie  arrangement  made  for  sup])orting 
the  plates  when  the  ram  is  lowered  and  the  press  is  leady  for  chaiging.  Instead  of 
the  links  shown  in  the  drawing,  the  long  edges  of  tlie  plates  are  formed  with  two 
projecting  ears.  The  gap  between  these  ears  is  the  same  on  all  the  plates,  and  fits 
on  to  a  vertical  flat  bar  fixed  between  the  toij  and  bottom  castings  on  each  side  of 
the  press.  The  breadth  of  tlie  ears  decreases  from  plate  to  plate  downwards,  so  that 
they  may  pass  farther  and  farther  down  between  a  pair  of  inclined  bars  similarly  fixed, 
and  ^\ith  steps  cut  on  their  facing  edges.  This  "  laider  "'  airangement,  as  it  is  called, 
has  the  advantage  that  it  dispenses  with  the  need  for  any  additional  means  of  fixing 
the  position  of  the  plates.  No  runners  are  required  on  the  insides  of  the  four  cohunns, 
for  the  inclined  bars  defuiitely  fix  the  position  of  the  plates  crosswise,  while  the  vertical 


^0. — Small  AuKlo-Americau  Press, 


60        THE   PRODUCTION   AND  TREATMENT   OF   \^GETABLE   OILS 

bars  fix  their  position  lengthwise.     Instead  of  solid  ears  four  pins  are  sometimes  to 
be  found  on  the  long  edges  of  the  plates  fulfiUmg  the  same  f miction. 

The  above  examples  may  be  taken  as  representing  the  standardised  design  of 
Anglo-American  presses.  This  standard  design,  it  may  Ije  repeated,  uses  a  ram  16  in. 
in  diameter,  and  a  working  pressure  of  2  tons  per  sc^uare  inch  on  the  ram.  It  turns 
out  at  one  pressing  sixteen  cakes,  each  weighing  from  10  lb.  to  12  lb.  Various  other 
sizes  of  press  are,  however,  made,  rangmg  from  a  twelve-cake  to  a  twenty-cake  press. 
The  pressure  emploj^ed  in  these  presses  is  in  general  the  standardised  2  tons,  and  as 
a  rule  the  diameter  of  the  ram  in  inches  is  equal  to  the  number  of  cakes  made  at  one 
pressing.  For  special  pui-poses  presses  using  3  tons  per  square  inch  are  made  in  the 
larger  sizes. 

Small  Akglo-Ajierican  Plaxt. 

As  a  contrast  to  these  regular-sized  presses,  we  illustrate,  in  Fig.  40,  an  Anglo- 
American  press,  by  Messrs.  ilanlove,  AUiott,  which  is  built  to  a  very  small  scale. 
The  engraving  shows  a  complete  self-contained  plant,  comprising  a  set  of  four-high 
chilled  reducing  rolls,  a  heatmg  kettle  with  steam  jacket,  meal-moistening  an-angement 
and  agitating  gear,  a  meal-moulding  machine,  and  a  twelve-cake  press,  operated  by 
hydrauhc  power.  The  plant  is  capable  of  dealing  with  about  a  ton  of  seed — containing 
not  more  than  3.5  to  40  per  cent,  of  oil — per  day  of  eleven  hours.  With  the  exception 
of  the  moulding  machine,  which  is  operated  by  hand,  the  entire  plant  is  driven  from 
the  belt  pulley  at  the  right-hand  end  of  the  overhead  comitershaft.  The  hydraulic 
power  for  the  press  is  supplied  by  a  horizontal  pump  mounted  on  the  press  head,  and 
driven  from  the  kettle  agitator  shaft  by  means  of  an  excentric  and  a  connecting  rod. 
It  will  be  noticed  that  the  press  plates  in  this  example  are  coupled  together  by  two 
sets  of  "  lazy  tongs."'  About  8  to  10  b.h.p.  is  required  to  drive  the  whole  plant.  For 
treating  verj'  oily  material  similar  smaU-sized  plants  are  made  with  a  press  of  the  cage 
type.  In  both  forms  two  presses  equivalent  in  output  to  the  one  shown  in  Fig.  40 
are  sometimes  suppUed,  so  that  the  whole  plant  may  be  run  more  or  less  continuously. 

Limitations  of  the  Anglo-American  System. 

The  Anglo-American  type  of  press  is  undoubtedly  an  efficient  piece  of  machineiy, 
and  possesses  certain  well-marked  advantages.  Thus,  it  is  comparatively  simple 
and  straightfonvard  in  design.  Running  in  conjunction  with  a  modem  meal-moulding 
machine  it  is  easily  and  quickly  loaded.  It  is  equally  easily  unloaded  after  the  meal 
has  been  pressed,  although  in  this  connection  it  is  to  be  remarked  that  the  stripping 
of  the  press  bagging  from  the  cakes  taken  from  the  press  may  involve  considerable 
labour,  so  much  so  that  in  some  mills  it  has  been  thought  advisable  to  install  special 
machines  which  permit  the  stripping  to  be  performed  mechanically  instead  of  by 
hand. 

At  the  same  time  the  general  design  of  this  type  of  press  is  not  altogether  free 
from  disadvantages.  One  obvious  drawback  lies  in  the  fact  that  the  cake  of  meal 
is  pres.sed  only  on  its  two  faces  and  not  simultaneously  roimd  its  edges.  This  defect 
is  partially  compensated  for  by  corrugating  the  press  plates  in  the  manner  we  have 
explained,  so  as  to  prevent  or  reduce  the  tendency  of  the  meal  to  spread.  This  expe- 
dient is  more  successful  with  some  materials  than  with  others.  Thus,  if  the  material 
being  cnished  is  castor  seed,  copra,  palm  kernels,  or  such  like  substances  of  a  very 
oily  nature,  the  mobility  of  the  material,  arising  from  its  high  oil  content,  commonly 
results  in  the  meal  spreading  excessively,  however  the  press  plates  may  be  shaped. 
If  the  spreading  is  excessive  more  oil  v>i\\  be  left  in  the  cake  than  is  desirable 


OIL    PRESSES— ANGLO-AMERICAN   TYPE  61 

or  profitable,  so  that  the  cakes  will  probably  have  to  be  again  reduced  to  meal,  and 
pressed  a  second  time.  Second  expression  oil  does  not,  however,  command  as  liigh 
a  price  as  first  expression  oil.  Consecpiently,  as  a  general  rule,  it  is  the  oil  seed  crusher's 
endeavour  to  extract  as  much  oil  as  possible  at  the  first  expression. 

A  second  disadvantage  of  the  Anglo-American  system  of  press  is,  like  the  first, 
of  importance  onlj"  when  very  oily  material  is  being  handled.  In  forming  such  material 
into  rough  cakes  in  the  moulding  macliine  it  is  difficult  to  carry  the  compression  as 
far  as  it  should  go  without  expressing  some  of  the  oil  from  the  meal.  If  this  undesirable 
expression  of  oil  is  to  be  avoided,  the  rough  cakes  put  into  the  main  press  must  be 
less  compressed,  and  consequently  thicker  than  usual.  As  a  result  the  press  has  to 
be  made  taller  by  a  corresponding  amount,  and  the  movement  of  the  ram  has  to  be 
increased  in  order  to  make  good  the  deficiency  in  the  preliminary  compression  of  the 
meal.  Under  the  high  hydraulic  pressures  in  use  the  latter  item  reacts  unfavoiuably 
on  the  upkeep  charges  of  the  press  generally,  and  of  the  ram  and  valves  in  particular, 
and,  in  addition,  increases  the  amount  of  jiressure  fluid  used  at  each  movement  of 
the  ram. 

It  will  be  gathered  from  these  remarks  that  the  Anglo-American  type  of  press 
is  best  adaj^ted  for  dealing  with  seed,  etc.,  containing  a  moderate  amount  of  oil.  For 
very  oily  seeds  a  press  is  required  which,  in  the  first  place,  supports  the  layer  of  meal 
round  its  edges  while  pressure  is  being  applied  to  its  faces,  so  that  the  meal  may  be 
evenly  pressed  and  prevented  from  spreading,  and  which,  in  the  second  place,  will  be 
able  to  work  without  the  assistance  of  a  separate  preliminary  moulding  machine. 
Sucli  an  appliance  is  the  box  cage  type  of  i^ress,  which,  in  several  different  forms,  has 
recently  come  into  extensive  employuient,  following  ujjon  a  great  increase  in  the 
amount  of  veiy  oily  seed,  etc.,  received  for  treatment.  In  our  next  chapter  we  will 
illustrate  and  describe  tj'pical  examples  of  cage  presses.  For  the  present  we  need 
only  say  that  the  cage  tj^pe  of  press  is  itself  not  wholly  free  from  disadvantages  peculiar 
to  its  design. 


CHAPTEE    IX 

OIL  PRESSES— CAGE   TYPE 

Ha\tng  described  and  disctissed  in  our  preceding  chapter  the  construction, 
working,  and  limitations  of  oil  presses  of  the  Anglo-American  type,  we  wUl  now  proceed 
to  deal  similarly  with  pres.*es  of  the  cage  type. 

Cage  Peesses. 

In  contrast  with  the  Anglo-American  type  of  press,  the  design  of  which  has 
reached  a  notable  degree  of  standardisation,  the  cage  type  of  press  is  made  in  many 
forms  which  are  sufficiently  distinct  to  merit  some  sort  of  classification  were  such  a 
course  likely  to  lie  of  any  value.  On  examination,  however,  it  will  be  found  that  the 
different  forms  differ  more  as  regards  the  general  arrangement  of  the  presses,  less  in 
the  details  of  their  design  and  not  at  all  in  their  princ.ple  of  action. 

As  illustrating  the  design  of  a  cage  press  and  its  method  of  working,  we  give  in 
Plate  II.  the  reproduction  of  a  drawing — specially  prepared  for  us  by  Messrs.  Manlove, 
Alliott,  of  Nottingham — sho^ving  the  construction  of  a  cagp  press  as  made  by  this 
firm.  Like  the  Anglo-American  press  by  the  same  makers,  described  in  our  previous 
chapter,  this  cage  press  is  provided  with  a  cast-iron  head,  four  forged -steel  columns 
with  buttress  threads,  a  cast-steel  cylinder  and  a  cast-iron  ram.  The  bottom  of  the 
press  is  formed  solidly  with  the  cylinder — a  practice  frequently  followed  also  in  the 
design  of  Anglo-American  presses — and  is  therefore  of  cast  steel.  A  circidar  cast- 
iron  oil  tray,  provided  on  its  underside  with  four  bosses  through  which  the  columns 
pass,  rests  on  top  of  the  cylinder  casting.  The  ram  rises  through  a  gland  at  the  centre 
of  this  tray.  Just  above  the  tray  four  split  muffs  a*ie  bohed  round  the  columns  to 
provide  stops  whereon  the  cage  in  its  lowest  position  may  rest. 

The  CoxsTRCcnox  of  the  Cage. 
The  cage  consists,  first,  of  a  cast-steel  top  piece  and  a  cast-steel  bottom  piece, 
bored  centrally  and  formed  with  four  ears  or  comers  suitably  concaved  to  fit  on  to 
the  press  cohunns.  Between  these  two  castings  are  arranged  a  number  of  vertical 
rolled-steel  bars,  the  ends  of  which  are  nicked  to  fit  into  an  annular  recess  in  the  top 
and  bottom  castings,  as  clearly  shown  in  the  sectional  elevation  given  in  Plate  II. 
The  bars  are  of  T  section  with,  however,  the  horizontal  limb  reduced  to  a  mere  fillet 
on  either  side.  The  bars  are  2  in.  deep,  while  the  fillets  measure  f  in.  The  faces  of 
the  fillets  are  machined  very  lightly  so  as  to  leave  alternate  high  and  low  portions  at 
5  in.  centres  throughout  their  whole  length.  The  bars  when  assembled  thus  bear 
against  their  neighlx)urs  at  every  .1  in.  of  their  lengths,  while  between  these  bearing 
points  narrow  spa«-s  are  left.  The  width  of  these  spaces  is  made  to  suit  the  class  of 
seed  to  be  pressed,  and  ranges  from  47?,to  in  to  c\  in  These  spaces  have  to 
be  sufficiently  large  to  allow  the  expressed  oil  to  flow  away  freely  through  them,  but 
not  so  large  that  the  meal  also  can  pass  out  of  the  cage.  Externally  the  bars  are 
stiffened  by  a  series  of  weldless  steel  rings.  Three  vertical  tie  reds  lying  jjist  outside 
the  rings  imite  the  top  and  bottom  castings  of  the  cage.     On  to  these  are  slipped  a 


INSERT  FOLDOUT  HERE 


OIL    PRESSES— CAGE    TYPE 


63 


number  of  ferrules  which,  fitting  between  the  rings,  hold  these  at  the  proper  distance 
apart.  Surrounding  the  bars  and  rings  there  is  a  cylindrical  lagging  of  sheet  steel 
united  tu  the  toj)  and  bottom  castings  of  the  cage.     This  lagging  prevents  the  expressed 


Fig.  41. — Two  Small  Cage  I'lx 


-Mauluvn,   Alllolt. 


oil  from  splashing  and  helps  to  guide  it  into  the  collecting  traj'  belo\N.  In  Fig.  41 
we  give  a  view  of  two  small  cage  presses  made  by  Messrs.  :\Ianlove,  Alliott.  This 
engraving  helps  to  make  clear  the  construction  of  the  cage. 

The  diameter  of  the  cage  is  equal  to  that  of  the  ram,  which  is  16  in.,  just  as  it 
was  in   the  case  of  the  Anglo -American  press  dosciibcd  in  the  preceding  chapter. 


64       THE   PRODUCTION  AND  TREATMENT  OF  VEGETABLE   OILS 

The  pressure  in  the  present  instance  is  3  tons  per  square  inch  as  compared  with  2  tons 
employed  in  the  cylinder  of  the  Anglo-American  press.  This  full  pressure  acts  on 
the  meal,  whereas  in  the  Anglo-American  press  the  pressure  on  the  cakes  is  much  less 
than  the  pressure  in  the  cylinder.  The  pressure,  in  fact,  is,  as  we  stated,  but 
I  ton  per  square  inch,  whereas  in  the  cage  press  illustrated  in  Plate  II.  it  is  3  tons 
per  square  inch.  The  employment  of  such  a  hig'.i  pressure  as  this  on  the  meal  in  an 
Anglo-American  press  would  be  next  to  impossible,  for  it  would  cause  even  the  least 
oily  of  meal  to  spread  excessively  between  the  plates.  Its  adoption  in  the  cage  press 
has  only  been  made  possible  by  reason  of  the  care  and  thought  which  have  been  given 


Fig.  42. -Cage  Press  and  Kettle  in  a  Mill. 

to  the  construction  of  the  cage.  It  may  be  taken  that  the  outward  pressure  on  the 
bars  of  the  cage  is  practically  3  tons  per  square  inch,  for  the  meal  during  the  pressing 
acts  almost  like  a  liquid  forced  out  of  a  cylinder  through  a  restricted  orifice.  Under 
these  conditions  the  greatest  care  is  necessary  in  designing  the  cage  to  ensure  that 
the  bars  shall  not  twist  or  bend  and  that  the  spaces  between  them  shall  remain  constant. 
How  this  is  secured  we  have  explained.  We  need  only  add  that  the  cages  of  similar 
presses  made  by  other  firms  are  constructed  on  the  same  principle. 

Immediately  above  the  cage,  as  shown  in  the  sectional  elevation  in  Plate  II  , 
a  cylindrical  cast-iron  head  is  slimg  from  the  underside  of  the  top  casting  of  the  press. 
This  head  is  moimted  on  a  four-wheeled  carriage  which  runs  on  a  pair  of  fixed  rails. 
The  movement  of  the  head  is  effected  by  means  of  a  hand  wheel  and  pinion  engaging 
with  a  rack  on  the  head      The  rack  is  sunk  into  the  top  of  the  head  so  that  a  plain 


OIL    PRESSES-CAGE   TYPE  65 

bearing  siu-facc  may  be  provided  between  the  head  and  the  underside  of  the  top  casting. 
Four  square-lieaded  studs  fixed  to  the  rails  form  stops  which  limit  the  movement  of 
the  head.  By  these  means  the  head  can  be  brought  directly  over  the  cage  when  every- 
thing is  leady  for  pressing,  or  removed  to  one  side  to  facilitate  the  loading  or  unloading 
of  the  cage  before  or  after  pressing. 

Method  of  Working  of  a  Cage  Press. 

In  Fig  42  \\L'  give  a  view  of  a  press  of  the  type  shown  in  Plate  II.  as  actually 
arranged  in  an  oil  mill.  It  will  be  noticed  that  the  press  is  disposed  about  half  abovo 
and  half  below  the  working  floor  level,  and  that  a  heating  kettle  is  placed  close  beside 
it.  \\'hen  the  cage  is  resting  on  its  bottom  stops  the  top  sui-face  of  its  upper  casting 
is  level  with  the  surface  of  the  plate,  hung  beneath  the  kettle,  on  which  the  strickling 
bo.\  slides.  With  the  movable  press  head  nni  back  out  of  the  way  the  strickling  box 
with  a  charge  of  meal  can  thus  be  pulled  over  to  discharge  its  contents  into  the  cage. 
Before  this  is  done,  however,  a  circular  steel  plate  is  dropped  into  the  mouth  of  the 
cage  so  that  it  maj'  come  to  rest,  a  short  distance  down,  on  four  catches  projecting 
through  the  walls  of  the  top  casting  of  the  cage.  A  circular  sheet  of  press  bagging  is 
placed  on  top  of  the  plate.  Thereafter  the  meal  is  striclded  in  a  layer  into  the  cage 
mouth.  The  plate  catches  are  mounted  on  a  ring  so  that  they  may  be  withdrawn 
simultaneously  to  allow  the  plate,  bagging  and  layer  of  meal  to  drop  down  on  to  the 
head  of  the  ram.  The  fall  allowed  is  not  great,  however,  for  the  ram  to  begin  with  is 
run  up  almost  to  the  top  of  the  cage,  and  as  the  loading  proceeds  is  allowed  to  descend 
slowly  to  keep  pace  M'ith  the  formation  of  the  layers  of  meal. 

The  layers  thus  formed  differ  from  the  cakes  placed  between  the  jjlates  of  an 
Anglo-American  press  in  the  fact  that  the  meal  is  cpiite  uncompressed.  To  take  full 
advantage  of  the  capacity  of  the  cage,  therefore,  strickling  is  continued  rmtil  the  ram 
reaches  the  bottom  of  its  stroke.  In  this  condition  about  haK  the  depth  of  the  bottom 
casting  of  the  cage  is  filled  with  meal.  When  jiressing  commences  this  meal  is  at  an 
early  stage  forced  upwards  into  the  cage  proper  and  there,  partially  at  least,  makes 
good  the  reduction  of  voliune  suffered  by  the  general  body  of  the  meal. 

When  the  cage  is  fully  charged  the  movable  head  is  run  back  over  it.  The  end 
of  the  head  is  turned  to  a  good  fit  with  the  bore  of  the  cage.  Just  before  pressure  is 
applied  to  the  meal  by  the  ram,  ^^ressure  is  admitted  to  two  auxiliai-y  ram  cylinders — 
see  A,  Fig.  41 — which,  acting  beneath  the  lower  casting  of  the  cage,  hft  the  cage  a 
short  distance  upward  so  as  to  cause  its  mouth  to  2Jass  on  to  the  cyUndrical  liead  and 
so  close  the  joint.  Pressure  is  then  admitted  to  the  main  cylinder.  As  the  expression 
of  the  oil  proceeds  the  cakes  of  meal  become  bound  tightly  against  the  walls  of  the 
cage.  The  friction  thus  developed  round  their  edges  is  sufficient  to  lift  the  cage  still 
further  on  to  the  head  as  the  compression  of  the  meal  increases.  In  other  words, 
no  ])rovision  is  made  to  bring  the  cage  as  it  rises  up  against  a  dead  stop.  This  is  an 
important  point.  Were  such  a  dead  stop  in  existence  the  friction  round  the  edges 
of  the  cake  would  result  in  the  cakes  being  subjected  to  an  effective  pressure  whicli 
would  decrease  from  cake  to  cake  upwards.  As  it  is  the  cage  "  floats  "'  with  the  meal, 
etc.,  inside  it,  and  the  effective  pressure  is  the  same  on  the  top  and  bottom  cakes. 
It  is  not,  however,  necessarily  the  same  towards  the  middle. 

When  the  cakes  have  stood  for  a  sufficient  length  of  time  under  pressure,  the 
main  ram  is  set  to  exhaust  until  the  cage  is  lowered  on  to  the  bottom  stops.  The 
auxiliarj'  hydraulic  cylinders  are  arranged  to  act  as  buffers  for  the  cage  so  as  to  biing 
it  cpiietly  to  rest.  The  movable  press  head  is  then  run  out.  In  its  outmost  position 
it  does  not  clear  completely  the  face  of  the  top  casting  of  the  cage,  and  therefore  forms 


66 


THE   PRODUCTION   AND   TREATMENT   OF   VEGETABLE   OILS 


a  stop  which  will  for  the  time  being  prevent  the  cage  from  rising.  Two  additional 
stops  are  ijrovided  for  the  opposite  side  of  the  top  casting  of  the  cage.  These  two  stops 
consist  of  half  caps  -which  can  be  swung  roinid  on  the  pillars  of  the  press.  With  these 
three  stops  in  action,  pressure  is  once  more  admitted  to  the  main  hj-draulic  cylinder, 
so  that  the  ram.  rising,  may  force  the  cakes  out  of  the  cage.  To  facilitate  the  ejection 
of  the  cakes  the  bore  of  the  cage  is  slightly  tapered,  so  that  its  diameter  at  the  top 
end  is  a  small  fraction  greater  than  at  the  lower  end.     Thus  a  slight  upward  movement 

of  the  cakes,  etc.,  in  the  cage  is  sufficient 
to  relieve  the  binding  pressure  round 
their  edges. 

In  general  the  cakes  produced  in  a 
l^ress  of  this  type  are  again  reduced 
to  meal  whicli,  after  being  heated,  is 
expressed  a  second  time.  A  cage  jjress 
can  be  used  for  this  second  expression, 
but  as  the  material  has.  now  had  the 
bulk  of  its  oil  removed,  it  can  quite 
convenientlj'  be  treated  in  an  Anglo- 
American  press. 

.Vlterxative  Cage  Press  Arrange- 
ments. 
The  press  just  described  is — as 
shown  in  Fig.  42 — arranged  to  work  by 
itself  in  conjunction  with  a  separate 
meal-heating  kettle.  Very  frequently, 
however,  cage  jiresses  are  worked  in  pairs 
or  in  sets  of  three,  the  two  or  the  three 
presses  in  each  set  being  quite  indepen- 
dent, except  in  so  far  as  they  are  fed 
from  a  common  kettle.  Li  Fig.  43  we 
give  a  view  of  a  two-press  set,  made  by 
A.  F.  Craig  &  Co.,  Ltd.,  of  Paisley.  The 
general  arrangement  of  this  set  is  shown 
in  Fig.  44.  This  engraving  incidentally 
indicates  the  nature  of  the  foundations 
required  for  an  oil  press.  The  presses, 
except  for  one  or  two  obvious  minor 
differences,  arc  similar  in  design  to  that 
already  descriljed.  The  method  of 
charging   the   cages   is,   liowcvcr,  quite 


Fig.  43. — Twin  Ciige  l're»ses — t'laig. 


different.  A  heating  kettle  is  arranged  over  the  presses,  being  supported  partially 
on  the  press  heads  and  partially  on  an  extra  pillar.  The  bottom  of  the  kettle  is  pro- 
vided with  two  outlet  holes  which  register  with  a  hole  formed  at  the  centre  of  each 
press  head — see  Fig.  44.  Each  outlet  is  controlled  by  a  pair  of  shutters,  one  above 
and  one  below  the  press  liead.  These  two  shutters  are  comiected  so  as  to  be 
operated  simultaneously.  Thus  a  double  movement  of  the  control  liandle  fills  the 
hole  in  the  press  head  with  meal  and  then  discharges  this  measured  quantity  into 
the  cage. 

An  alternative  arrangement  by  Manlove,  Alliott  &  Co.,  Ltd.,  is  indicated  in 


OIL    PRESSES— CAGE   TYPE 


67 


Fig.  45.  This  arrangement  is  particularly  suitable  where  large  presses  are  required. 
It  consists  of  a  battery  of  four  presses,  a  separate  compressor  and  extractor  press  and 
a  power-driven  travelling  carriage.  The  compressor  and  extractor  press  is  i^rovided 
with  a  movable  head,  as  in  the  case  of  the  presses  described  above,  so  that  its  cage 


The   Engineer" 


Swain   Sc. 


Fig.  44. — Twin  Cage  Presses — Craie;. 


may  readily  be  charged  with  layers  of  meal  from  the  adjacent  kettle.  The  cage  may 
be  regarded  as  being  in  two  parts,  the  lower  of  whicli  is  fixed,  in  so  far,  at  least,  as  the 
position  of  its  centre  line  is  concerned,  while  the  upper  part  can  ho  run  out  on  to  cross 
rails  on  tiie  top  of  the  travelling  carriage.  The  strickling  proceeds  until  both  parts  are 
filled  with  layers  of  meal.     Pressure  is  then  applied  in  the  ram  cybnder  so  as  to  com- 


68        THE   PRODUCTION   AXD   TREATMENT   OF   VEGETABLE   OILS 


press  all  the  meal  into  the  upper  movable  part  of  the  cage.  When  this  is  accomplished 
the  pressure  is  released,  and  the  movable  part,  of  the  cage  is  run  out  on  to  the  travelling 
carriage,  which  then  transports  it  to  one  of  the  four  main  presses.  The  travelling 
carriage  is  provided  with  two  sets  of  cross  rails  so  that  it  maj^  support  a  cage  ready 
for  pressing,  while  giving  accommodation  for  the  reception  of  a  cage  the  pressing  of 
which  has  been  completed.  On  the  return  joumej-,  therefore,  the  carriage  brings 
back  to  the  preliminary  press  a  cage  from  which  the  cakes  are  ready  to  be  extracted. 
This  extraction  is  performed  at  the  preUminary  press  in  the  manner  indicated  ah-eady 
for  the  single  press  by  the  same  makers. 


'^^^^■^^^ 


"Tilt  Engineer" 

Fig.  45. — Battery  of  Four  Cage  Presseb — Maulove,  Alliott. 

The  preliminary  press  used  in  this  system  of  working  is,  we  think,  to  be  regarded 
properly  as  the  equivalent  of  the  moulding  machine  required  with  an  Anglo-American 
type  of  press.  Its  adoption  has  the  distinct  advantage  that  tlie  main  presses  can  be 
made  with  fixed,  and  not  sliding  heads.  Further,  it  will  be  gathered  that  as  the 
"  slack  "  in  the  meal  is  taken  up  in  the  preliminary  press,  the  movement,  and  therefore 
the  length,  of  the  rams  in  the  main  presses  can  be  made  quito  siiort. 

Revol%tn'g  Cage  Press. 
Another  interesting  and  important  alternative  arrangement  of  working  cage 
presses  in  groups  lies  in  the  adoption  of  a  rotarj'  principle.     An  example  of  the  apphca- 


INSERT  FOLDOUT  HERE 


OIL    PRESSES— CAGE   TYPE 


69 


tion  of  this  principle  is  illustrated  in  Plate  III.,  where  we  show  a  revolving  cage 
press  made  by  A.  F.  Craig  &  Co.,  Ltd.,  of  Paisley,  under  Craig  and  Morfitt's  patent, 
A  photograpli  of  such  a  press  is  reproduced  in  Fig.  46. 


Fig.  4G. — Revolving  Cage  Press — Craig. 

The  fundamental  featuic  of  the  design  hcs  in  the  provision  of  three  cages  arranged 
with  their  centres  at  the  apices  of  an  equilateral  triangle,  the  whole  being  rotatable 
as  a  block  round  an  axis  passing  through  the  centre  of  the  triangle.  Corresponding 
to  the  three  cages  there  are  three  fixed  press  heads  ?,nd  three  hydraulic  cylinders  and 
rams,  arranged  with  their  centres  at  the  apices  of  an  identical  equilateral  triangle. 


70        THE   PEODUCTIOX   AaD  TREATMENT   OF   \'EOETABLE   OILS 

During  a  complete  rotation  of  the  cages  about  their  common  axis  each  cage  passes 
in  tuni  between  each  press  head  and  its  corresponding  hydraulic  ram.  The  method 
of  working  is  to  fill  cage  A — see  Plate  III. — with  meal  from  an  adjacent  kettle, 
while  it  stands  beneath  one  of  the  press  heads,  and  to  give  the  meal  in  it  at  this  point 
a  iJieiiminary  com^jression.  The  cage  system  is  then  rotated  clockA\ise  through  120 
degrees,  so  as  to  bring  cage  A  beneath  the  second  press  head  where  the  meal  is  subjected 
to  an  intermediate  compression,  and  so  as  to  bring  cage  C  into  the  position  formerly 
occupied  by  cage  A.  Cage  A  is  allowed  to  stand  under  pressure  while  cage  C  is  being 
emptied  and  recharged  ^^"ith  meal.  Thereafter  a  further  rotation  of  the  cage  system 
through  120  degrees  brings  cage  A  beneath  the  third  press  head  where  its  meal  receives 
the  final  compression.  Meanwhile,  cage  C  is  receiving  its  intermediate  compression 
beneath  the  second  press  head,  while  cage  B  beneath  the  first  press  head  is  Ix-ing 
emptied  and  recharged.  A  final  rotation  of  the  cage  system  brings  cage  A  back  again 
beneath  the  fii'st  press  head  for  emptying  and  recharging.  The  meal,  it  \\ill  be  seen, 
is  pressed  in  three  sepai-ate  .stages.  It  will  also  be  gathered  that  the  arrangement 
secures  practically  continuous  working.  It  is  stated  that  even"thing  about  a  set  of 
these  presses  can  be  worked  by  one  \niskiUed  man  with  the  assistance  of  a  boy. 

The  detailed  design  of  the  press  is  noteworthy.  The  meal-heating  kettle  is  of 
the  usual  type,  and  is  fitted  with  the  usual  means  of  stirring,  heating  and  moistening 
the  meal.  It  is  sujaported  partly  on  the  first  press  head  and  jjartly  on  two  separate 
colunnis.  The  strickling  box  slides  on  a  surface  with  guiding  edges  formed  on  top 
of  the  fii-st  press  head.  A  circular  hole  equal  in  diameter  to  the  bore  of  the  cage  is 
formed  in  the  press  head,  and  is  provided  with  four  catches,  o^jerated  simultaneously, 
for  temporarily  supporting  the  usual  steel  disc  and  cireular  piece  of  press  cloth  on  to 
which  the  meal  is  deposited  from  the  strickling  box.  The  withdrawal  of  the  catches 
allows  the  plate,  cloth,  and  layer  of  meal  to  fall  on  to  the  ram  head.  Dm-ing  the 
charging  operations,  the  ram  starting  from  its  highest  position  is  allowed  slowly  to 
faU.  Oliarging  is  continued  until  not  only  the  cage,  but  the  compression  chamber — D 
in  Plate  III. — beneath  it  is  completely  filled.  ^Mien  this  stage  is  reached,  a  run-out 
shde,  operated  by  racks,  pinions  and  hand  wheel,  is  moved  back  to  close  the  opening 
in  the  press  head  from  the  underside.  Tliis  shde  is  provided  with  a  shallow  circular 
boss  turned  to  fit  the  bore  of  the  cage. 

^Yhen  matters  are  in  this  condition,  two  auxihaiy  hydraulic  rams  are  brought 
into  action  beneath  the  compression  chamber  wliich.  lifting  this  chamlier  and  the  cage. 
clo.-*e  the  joint  between  these  two  parts  and  also  the  joint  between  the  cage  and  the 
run-out  slide  beneath  the  press  head.  Pressure  is  then  appUed  beneath  the  main 
ram  which,  rising  through  the  compression  box.  compresses  the  meal  entirely  into 
the  cage.  A  cei-tain  amomit  of  oil  is  forced  out  of  the  meal  at  this  stage,  and  is  caught 
iji  a  tray  beneath  the  press.  Even  before  the  meal  is  entirely  pushed  out  of  the  com- 
pression box,  the  pressure  may  be  sufficient  with  some  seeds  to  express  a  portion  o.' 
the  oil  from  the  meal.  For  this  reason  the  top  end  of  the  compression  chamber  is 
finely  perforated,  so  that  the  oil  expressed  may  escape  readily.  "\Mien  the  pressure 
of  the  main  ram  is  relieved,  the  meal  layers  tend  to  expand  a  little.  To  obviate  any 
trouble  which  this  expansion  might  cause  when  it  comes  to  rotating  the  cages,  the 
meal  is  compressed  further  into  the  cages  than  would  be  necessary  were  expansion 
absent. 

The  compression  suffered  by  the  meal  in  the  preliminary  press  is  sufficient  to 
bind  the  buUc  of  it  witliin  the  cage,  so  that  when  the  ram  falls  it  remains  there.  The 
steel  plate  and  the  press  cloth  at  the  foot  of  the  cage  and  one  or  two  of  the  lowest 
layers  of  meal  require,  however,  to  be  supported  when  the  ram  is  lowered  and  while 


OIL  PRESSES— CAGE    TYPE  71 

the  cage  is  being  <u;ncd  round  to  come  beneath  the  second  and  third  press  heads. 
This  sui)port  is  given  by  a  pair  of  spring  catches  arranged  in  the  lower  end  casting  of 
the  cage.  These  catches  sHp  in  beneath  the  lowest  press  plate  as  the  ram  falls.  They 
are  automatically  pushed  back  by  the  second  and  third  rams  when,  these  rise  into  the 
cage  and  fall  into  action  again  when  these  rams  are  lowered.  Means  have  to  be  provided 
at  the  preliminaiy  press,  whereby  the.se  catches  may,  while  the  press  is  being  charged, 
be  rendered  inoperative,  so  that  they  shall  not  prevent  the  charge  from  passing  down 
into  the  compression  chamber.  These  means  consist  of  links  and  levers  operated 
from  the  long  handle  F  shown  in  Plate  III. 

The  manner  in  which  the  cages  are  moiuited  requires  a  word  of  explanation. 
They  have  to  be  free  to  revolve  together  about  their  common  axis,  and  at  the  same 
time  have  to  be  free  to  rise  vertically  a  short  distance  under  the  action  of  the  auxiliaij- 
hydranlic  rams,  so  that  the  joints  between  them  and  the  press  heads  may  be  closed 
before  the  main  ram  is  brought  into  action.  The  support  for  the  cages  consists  primarily 
of  a  central  vertical  hollow  cylindrical  casting — G  in  Plate  III — within  which  are 
disposed  the  inner  columns  carrying  the  stationary  press  heads.  This  cylindrical 
casting  is  supported  at  its  bottom  flange  on  a  series  of  rollers  journalled  in  a  casting 
fixed  on  top  of  the  lower — stationary — castings  of  the  three  presses.  The  position  of 
its  axis  is  fixed  by  means  of  three  horizontal  rollers  joiirnalled  on  the  fixed  roller 
casting  and  bearing  against  the  interior  of  the  cylindrical  casting — see  the  plan  view 
in  Plate  III. 

The  top  flange  of  the  cylindrical  casting  is  splayed  out  into  the  form  of  a  six -armed 
spider.  A  little  more  than  half-way  down  a  similar  set  of  six  arms  projects  from  the 
casting.  The  cages  are  situated  between  alternate  pairs  of  these  arms  and  are  united 
thereto  by  means  of  rods  running  between  the  top  and  bottom  cage  end  castings  and 
passing  through  eyes  in  the  ends  of  the  arms.  The  cages  are  thus  free  to  rise  vertically, 
but  are  compelled  to  rotate  solidly  with  the  central  cylindrical  casting. 

From  the  spider  arms  six  brackets — not  shown  in  Fig.  46,  but  clearly  indicated 
in  Plate  III. — depend  and  supporti,  crinohne-wise,  a  circular  rack  which  encloses 
all  three  cages  at  the  level  of  their  bottom  castings.  This  ring  passes  close  to,  but 
within  the  outer  columns  supporting  the  jjress  heads,  and  is  provided  with  additional 
carrying  means  in  the  shape  of  three  rollers  mounted  on  the  bottom  castings  of  the 
presses  and  bearing  against  its  underside.  The  ring  meshes  with  a  pinion  on  a  vertical 
shaft  provided  with  a  hand  wheel.  By  turning  this  hand  wheel  the  ring,  central 
casting  and  cages  are  rotated  as  one  body  from  one  setting  to  the  next. 

In  the  press  illustrated  in  Plate  III.,  the  cages  are  19  in.  in  diametei  and  54  in. 
long.  The  extension  chamber  at  the  preliminaiy  press  is  42  in.  long.  These  dimensions 
give  the  press  a  capacity  of  about  20  cwt.  of  copra  i^er  hour.  The  diameters  of  the 
lower  ends  of  the  first  and  second  rams  are  less  than  the  diameter  of  the  cage.  Conse- 
quently, the  preliminary  and  intermediate  pressures  on  the  meal  are  less  than  the 
pressure  admitted  to  the  hydraulic  cylinders.  The  lower  end  of  the  third  ram  is  of 
greater  diameter  than  the  cage,  so  that  the  final  picssure  on  the  meal  is  greater  than 
the  hydraulic  pressure  in  use.  With  a  hydraulic  pressTire  of  2  tons  per  square  inch, 
the  pressures  on  the  meal  work  out  at  the  following  values  :  Preliminary  press,  1 1  cwt.  ; 
intermediate  press,  30  cwt.  ;  final  press,  60  cwt.  per  square  inch.  A  high  final  pressure 
is  thus  obtained  without  employing  an  equally  high  hydrauhc  pressure.  This  is  of 
importance,  because  al  a  pressuie  of  3  tons  ])er  sqiiare  inch  the  wear  and  tear  on  the 
pumps  and  valves  of  the  hydraulic  pressure  supply  system  is  apt  to  become  a  serious 
item  in  th^  upkeep  charges. 

A  sciiedule  of  working  times  for  this  press  has  been  supplied  to  us  by  the  makers. 


72        THE   PRODUCTION   AND   TREATMENT   OF   VEGETABLE   OILS 

According  to  this,  eight  minutes  are  allowed  for  emptying  and  filling  the  cage  at  the 
preliminary  press.  It  is  allowed  to  stand  under  pressure  for  seven  minutes  at  this 
press.  One  half  minute  is  consumed  in  lowering  the  rams — all  three  rams  are  lowered 
simultaneously — and  another  half  minute  is  required  to  change  the  jjositions  of  the 
cages.  Thus  tlie  meal  is  imder  pressure  for  seven  minutes  in  the  preliminary  press, 
fifteen  minutes  in  the  intermediate  and  fifteen  minutes  in  the  final,  or  altogether, 
thirty-seven  minutes  out  of  a  total  working  time  of  forty -eight  minutes. 

Other  Arrangements  of  Cage  Pres.ses. 

Various  other  forms  or  cage  presses  are  made.  We  can,  however,  but  briefly 
mention  two,  both  made  by  Robert  Middleton  &  Co.,  of  Leeds.  One  of  these,  Lambert's 
patented  "  continuous  "  oil  press,  is  of  the  revolving  type,  but  instead  of  having  three 
cages,  as  in  Messrs.  Craig's  press  described  above,  it  has  but  two,  one  for  the  jjreliminary, 
and  the  other  for  the  final,  pressing  of  the  meal.  The  meal  is  fed  into  the  preliminary 
press  at  the  foot  instead  of  at  the  top  of  the  cage  by  means  of  a  pair  of  circular  steel 
boxes  mounted  on  a  table  which  rotates  about  one  of  the  press  columns  in  such  a  way 
that  while  one  box  is  beneath  the  preliminaiy  press,  the  other  is  beneath  the  kettle 
receiving,  a  charge  of  meal.  In  another  arrangement  by  the  same  makers,  the  kettle 
works  in  conjunction  with  a  preliminaiy  press  much  in  the  way  illustrated  in  Fig.  45. 
Instead,  however,  of  the  main  presses  being  arranged  in  a  row,  they  are  in  this  case 
arranged  on  the  arc  of  a  circle.  The  cages  are  transported,  when  filled,  from  the 
preliminary  jjress  to  the  main  presses  on  a  turntable  provided  witli  rails  and  hj'draulic 
ruiuiing-out  gear. 

The  chief  objection  which  can  be  urged  against  the  cage  type  of  oil-press  is  that 
its  construction,  compared  with  the  Anglo-American  type,  is  complicated.  Its 
successful  working  depends  very  largely  on  the  care  given  to  the  design  and  construction 
of  the  cage  This,  as  may  be  su^jposed,  is  an  expensive  item.  Efforts,  therefore,  have 
been  made  to  cheapen  the  cost  of  manufacture,  while  retaining  the  principle  of  the 
cage  press  by  substituting  for  the  cage  built  up  of  vertical  bars,  a  cylindrical  box  of 
verj'  finely  perforated  sheet  steel. 


CHAPTER  X 

THE   GENERAL   ARRANGEMENT   OF   OIL  MILLS 

Having  described  in  the  two  preceding  chapters  the  construction  and  working 
of  tyijical  modern  oil  presses,  it  is  desirable  that  we  should  now  briefly  deal  with  the 
general  arrangement  of  oil  mills  and  with  some  of  tlie  machines  and  appliances  which, 


■  :  i 

"tme    Enoinees"  Swain   Sc. 

Fig.  47. —  Cross  Section  of  a  Mill  with  Anglo-American  Presses — Eose,  I)o\Tns  &  Thompson. 

in  addition  to  the  rolls,  kettles,  moulding  machines,  and  so  on.  already  described,  are 
commonly  to  be  found  installed  therein. 

Anglo-Asierican  Oil  Mill. 
In  Fig.  47  we  give  a  cross-sectional  elevation  of  a  tjqiical  oil  mill  arrangement  as 
carried   out   by  Rose,  Downs,  &  Thompson,  Ltd.,  of  Hull.      The    plant  shown  can 
treat  per  hour  15  to  18  cwt.  of  linseed  or  similar  small  seed  requiring  only  one  pressing. 


74        THE   PRODUCTIOX   AXD  TREATMENT   OF   VEGETABLE   OILS 

At  A  is  shown  a  set  of  5-high  cnishing  rolls  of  standard  design.  The  individual  rolls 
are  3  ft.  6  in.  long,  and  have  an  average  diameter  of  about  10  in.  The  general  design 
is  simUar  to  that  of  the  examples  illustrated  and  described  in  a  previous  chapter.  From 
these  rolls  the  crashed  seed  is  conveyed  by  a  small  chain  bucket  elevator  B  into  the 
meal-heating  kettle  C.  The  kettle  follows  the  usual  design,  and  is  5  ft.  in  internal 
diameter  by  2  ft.  2  in.  deep.  It  is  lagged  with  hair  felt  and  is  provided  with  a  steam 
reducing  valve  and  a  steam  trap  for  the  exit  of  condensed  water.  The  moulding 
machine  D  receives  the  hot  meal  from  the  kettle  in  the  manner  we  have  already 
descril^ed.  and  reduces  each  charge  of  meal  from  an  imconsolidated  layer  3  in.  tliick 
to  a  rough-formed  cake  1|  in.  thick.  The  four  presses  E  are  of  the  standard  Anglo- 
American  design  and  size.  Each  is  capable  of  making  at  a  charge  sixteen  cakes,  measur- 
ing about  28  in.  by  12  in.  and  weigliing  10  to  11  lb.  each.  The  press  rams  are  16  in.  in 
diameter  and  work  under  a  pressure  of  2  tons  per  square  inch.  The  presses  stand  in 
a  steel  tank  sunk  into  the  floor.  The  expressed  oil  is  caught  in  this  tank  and  is  drawn 
thence  by  an  oil  piunp  and  forced  into  storage  vessels.  These  vessels  have  a  capacity 
of  50  tons,  and  are  pro^^ded  vrith.  oil  taps  and  with  additional  taps  whence  may  be 
drawn  any  mucilage  which  may  settle  out  from  the  oil  on  standing. 

The  cakes  taken  from  the  press  are  stripped  of  their  bagging,  and  one  by  one  are 
placed  on  the  table  of  a  power-driven  paring  machine  F.  With  these  machines  we 
will  deal  presently.  Their  fimction  is  to  pare  off  the  extra  oily  edges  of  the  cakes  so 
as  to  trim  the  cakes  to  a  more  or  less  unifonn  size,  and  fiuther,  to  recover  the  oily 
edge  portions  for  additional  treatment.  The  parings  are  passed  into  an  edge  runner  G 
where  they  are  reduced  again  to  the  fonn  of  meal.  This  meal  is  then  returned  by 
means  of  the  elevator  H  to  the  kettle  C,  where  it  is  mixed  with  a  fresh  charge.  The 
edge  stones  are  of  Derbyshire  giit  4  ft.  in  diameter  by  12  in.  thick.  Besides  reducing 
the  parings  to  the  form  of  meal,  they  are  also  used  to  treat  likewise  any  broken  or 
damaged  cakes  arising  from  the  working  of  the  presses. 

Hydraulic  pressure  is  supplied  to  the  presses  by  a  set  of  horizontal  belt-driven 
pumps  J.  Xo  accumulators  are  used.  The  base  of  these  pumps  forms  a  cistern, 
whence  the  pirmps  draw  their  supply  of  pressure  fluid — oil  usualh' — and  to  which 
the  exhaust  from  the  presses  is  deUvered.  In  working  oil  presses  there  are  two  di-stinct 
periods.  During  the  first  the  meal  and  press  bagging  are  closing  up.  The  resistance 
experienced  by  the  press  ram  is  an  increasing  quantity,  and  the  movement  of  the  ram 
is  considerable.  During  the  second  period  the  meal  is  left  standing  under  pressure. 
The  resistance  on  the  ram  is  now  constant,  and  its  movement  is  practically  zero.  It 
is  distinctly  economical  to  use  a  low  pressure  on  the  ram  during  the  first  period,  followed 
by  a  higher  pressure  during  the  second.  In  addition,  it  is  fomid  desirable  to  use  a  low 
pressure  durmg  the  earlier  period,  because  if  a  liigh  pressure  is  used  the  chances  of 
the  meal  spreading  are  increased  and  the  press  bagging  is  likely  to  be  quickly  damaged. 
These  considerations  are  also  of  importance  at  the  moment  when  the  change  over 
from  low  to  high  pressure  is  being  made.  The  change  should  not  be  made  suddenly  ; 
the  pressure,  rather,  should  gi"OW  gi'adually  to  its  maximum  value.  This  is  secured 
usually  by  employing  regulating  valves  of  a  suitable  t  j-pe.  The  pumps  in  the  installa- 
tion illustrated  in  Fig.  47  have  two  low-pressure  barrels  3  in.  in  diameter  and  two 
high-pressure  barrels  1|  in.  in  diameter. 

The  whole  plant  is  driven  by  a  single-cylinder  horizontal  engine  of  45  i.h.p.  running 
at  100  revolutions  per  minute.  The  steam  supply  is  obtained  from  a  Lancasliire 
boiler  20  ft.  long  by  6  ft.  diameter.  This  is  more  than  large  enough  to  meet  the 
demands  of  the  engine.  It  has,  of  course,  in  addition  to  supply  steam  for  the  heating 
kettle  and  to  the  moulding  machine.     The  latter,  in  the  absence  of  a  low-pressure 


INSERT  FOLDOUT  HERE 


THE  GENERAL  ARRANGEMENT  OF  OIL  MILLS 


75 


accumulator,  has  to  be  of  the  steam -operated  type.  The  whole  plant  illustrated 
occupies  a  room  measuring  34  ft.  by  28  ft.  by  18  ft.  high,  and  engages  per  shift  the 
attention  of  three  men,  not  counting  the  boiler  and  engine  attendant. 

Cage  and  Anglo-American  Presses  in  Combination. 

The  ground  plan  of  a  mill — also  by  Rose,  Downs  &  Thompson — for  treating 
seeds  which  rec[uire  to  be  pressed  twice,  is  shown  in  Fig.  48.  The  seed  received  at  A 
is  passed  through  a  set  of  rolls  B  and  is  conveyed  by  an  elevator  C  to  a  kettle  D.  If 
the  first  pres.sing  is  to  be  carried  out  cold  no  steam  is  admitted  to  the  jackets  of  this 
kettle.  The  meal,  hot  or  cold,  is  distributed  from  it  into  two  cage  presses E,  E  beneath 
it.     The  round  cakes  left  after  the  first  pressing  are  broken  up  in  a  cake  breaker  F, 


Tne    Enoineer"  Swain    Sc 

Fig.  4.S. — Plan  of  Mill  with  Cage  and  Anglo-American  Presses — Rose,  Downs  &  ThomiJson. 

and  are  taken  by  an  elevator  G  to  a  disintegrator  H,  where  the  pieces  are  reduced  to 
meal  again.  An  elevator  J  then  conducts  the  meal  to  a  second  kettle  K  and  a  moulding 
machine  L.  The  second  pressing  is  conducted  in  a  set  of  four  Anglo-American  presses 
M.     The  paring  machine  is  showii  at  N  and  the  hydraulic  pumps  at  P. 

The  oil  mill  arrangements  represented  in  Figs.  47  and  48  may  be  regarded  either 
as  complete  in  themselves  or  as  units  of  larger  mills. 


Cage  Press  Oil  ^Iill. 
In  Plate  IV.  we  reproduce  the  general  arrangement  drawing  of  an  oil  mill 
equipped  with  cage  presses,  all  the  machinery  for  which  was  supplied  by  A.  F.  Craig 
&  Co.,  Ltd.,  of  Paisley.  The  mill  as  here  shown  was  specially  designed  for  treating 
copra,  but  by  suitably  varying  the  preparatoiy  crushing  portion  of  the  plant  it  can 
be  used  for  treating  any  kind  of  seed  or  nut.  Its  designed  capacitj'  is  10  cwt.  of  copra 
per  hour  if  one  pressing  only  is  given  to  the  material,  and  8|  to  9  cwt.  if  it  has  to  be 
pressed  twice.  The  cage  presses,  two  in  number,  are  fed  with  hot  meal  from  an  over- 
head kettle,  the  arrangement  being  in  general  on  the  lines  of  the  pair  of  presses  by 
Messrs.  Craig,  illustrated  in  Fig.  44  of  our  preceding  chapter.     Each  cage  is  19  in. 


76         THE   PRODUCTION   AXD  TREATJIENT   OF   ^'EGETABLE   OILS 

in  internal  diameter  by  100  in.  long.     The  rams  are  181  in.  in  diameter  and  work 
under  a  pressure  of  '2  tons  per  square  inch. 

The  material  is  first  passed  tlirough  a  set  of  reducing  rolls  IS  in.  wide.  From 
these  it  is  raised  by  an  elevator  and  dropped  into  the  hopper  of  a  set  of  shredding  and 
crushing  rolls.  36  in.  wide,  of  the  type  illustrated  in  Fig.  4  of  our  tliird  chapter.  A 
second  elevator  then  lifts  the  material  to  the  meal  kettle  at  the  top  of  the  presses. 
The  expressed  oil  collects  in  a  receiving  tank  and  is  thence  forced  by  an  oil  pump. 


The   Engineer 


Fig.  49. — High  and  I/jw-Pressure  OH  Press  Pump — ^Craig. 


with  a  ram  3  in.  in  diameter  by  3  in.  stroke,  into  a  storage  vessel.  The  whole  plant 
is  driven  by  a  50  b.h.p.,  single-cylinder,  horizontal  engine  supphed  with  steam  at 
100  lb.  pressure  by  an  18-ft.  Cornish  boiler.  The  labour  required  to  operate  the  plant 
consists  of  two  men  for  the  presses  and  a  man  or  a  bov  to  attend  to  the  reducing  and 
crushing  rolls.  A  second  shift,  similar  to  the  above,  is  required  for  night  working, 
as  the  plant  is.  as  usual,  run  cont:nuously.  In  addition  to  these,  two  men  are  required 
to  look  after  the  oil.  the  cakes,  and  the  storage  of  the  copra.  These  men,  however, 
work  only  during  the  day  shift. 

HYDKArLic  PrMprKG  EgrrPMEST. 
As  in  the  case  of  the  mill  arrangement?  illustrated  in  Fig?.  47  and  48,  the  presses 
represented  in  Plate  IV.  are    operated  •  directly  by  pumps   without    accumulators. 


THE  GENERAL  ARRANGEMENT  OP  OIL  MILLS 


77 


Each  press  has  its  own  pump,  so  that  it  may  be  worked  entirely  independently  of 

t  he  other.     In  Figs.  49  and  50  we  give  the  reproductions  of  a  drawing  and  a  photograph, 

whicli  will  enable  the  construction  of  the  pumps  to  be  understood.     They  are  of  a 

horizontal,    belt-driven    type,  and   are 

mounted  on  top  of  a  cast-iron  suction 

tank    for    the     hydraulic    fiuid.      An 

adcUtional    suction    tank,    it    will     be 

Udliced  from  the  general  arrangement 

drawing,    is    also    provided    for    each 

pump.      Each   pump   has    four    rams, 

all    of    3   in.    stroke.      The   rams    are 

reciprocated  by  a   crankshaft  running 

at   about   60   revolutions   per   minute, 

and  working  within  blocks,  which  can 

slide  vertically  in  crossheads,  to  which 

the  rams,  suitably  guided,  are  attached. 

On  one  side  of  the  crosshead  the  rams 

are  2J  in.  in  diameter,  and    generate 

the  low  pressure  required  during    the 

early  stages  of  the  pressing,  as  above 

explained.    The  two  high-pressure  rams 

on  the  other  side  of  the  crosshead  are 

1  in.  in  diameter.     All  four  rams  draw 


Fig.  50. — Oil  Press  Pump. — Craig. 


from  the  pump  cistern  through  separate  pipes  extending  downwards  from  (he  valve 
liox.  Their  action  is  united  during  the  earlier  stage  of  the  pressing,  but  when  a  pressure 
of  700  lb.  is  reached  in  the  press  cyhnder,  the  low-pi-essure  rams  are  automatically 

shut  down,  while  the  high-pressure  rams 
continue  the  work  until  the  fuial  pressure 
of  2  tons  is  reached.  This  effect  is 
obtained  by  means  of  a  weighted  lever 
mounted  on  top  of  the  valve  box  and 
connected  by  a  rod  and  lever  to  a  I'od 
passing  up  each  low-pressure  suction  pipe. 
The  latter  rod  acts  upon  the  low-pressure 
suction  valves  in  such  a  way  that  when 
it  rises  it  throws  these  valves  out  of 
action  and  causes  the  delivery  from  the 
low-pressure  rams  to  pass  back  again 
into  the  cistern.  The  rise  of  the 
weighted  lever  when  700  lb.  pre.ssure  is 
reached,  is  brought  about  by  a  plunger 
acting  beneath  it  close  to  its  fulcrum. 
A  second  weighted  lever  on  the  high- 
pressure  side  of  the  valve  box  constitutes 
the  working  element  of  a  safety  valve, 
which  prevents  the  pressure  generatedfrom 
rising  above  2  tons  per  square  inch.  The 
pumps  are  provided  with  fa.st  and  loose  belt  pulleys,  but  during  a  spell  of  working  they 
can  be  allowed  to  run  contmuously,  their  deliveiy  when  not  actually  recpiired  at  the 
presses  being  returned  at  the  press  control  valves  back  into  the  auxiliarv  suction  tanks. 


Fig.  51. — Oil  Mill  Accumulators- — Rose,  Downs 
&  Thompson. 


78        THE   PRODUCTION   AND   TREATMENT   OF   VEGETABLE   OILS 

Accumulators. 

The  method  of  worlcing  hydrauHc  oil  presses  without  accumulators,  exemplified 
in  the  above  mill  arrangements,  entails  the  use  of  a  separate  pump  for  each  press  if 
the  presses  are  to  be  capable  of  being  operated  independently.  Naturally,  therefore, 
this  method  is  best  suited  to  the  case  of  oil  mills  having  but  few  presses,  in  such 
cases,  little,  if  anything,  is  to  be  gained  by  adopting  accumulators  ;  indeed,  these 
may  well  be  but  an  added  complication,  and  entail  the  provision  of  more  floor  space 


1^ 

■^M^^^V^^^^I 

'  /   1  ^ 

H 

M 

i 

^^^P 

»?^«i^t 

^^^^^^^ 

^ 

mE 

•    < 

^K 

^^^^^^^Hr''      '^<l 

■PI 

--j^gi 

^^^H 

■c^l'. 'I'lr     '^^1 

W>*i 

■1 

Wmi 

1 

-k^^^^^^^lal 

m 

^ 

isl 

ly 

^^^3BI 

^^^^^1 

■M 

_.  ■ 

-  '^w 

^^^^H 

iH^^S...:.^S 

Fig.  52. — Accumulators  in  aii  Oil  Mill — Manlovo,  Alliott 

* 

and  head  room  than  is  strictly  economical.  When,  however,  the  number  of  presses 
in  tlie  mill  exceeds  a  certain  figure,  a  point  is  reached  at  which  both  first  cost  and 
floor  space  will  be  economised  by  providing  accumulators — worked  by  one  or  two 
pumps — rather  than  separate  pumps  for  each  press.  Practice  implies  that  this  point 
is  in  general  regarded  as  having  been  reached,  when  there  are  eight  or  more  presses 
in  the  mill. 

When  accumulators  are  installed,  it  is  usual  to  find  one  arranged  for  a  high -pressure 
supply  working  in  conjunction  with  one  or  more  for  a  low-pressure  supply.  An 
additional  advantage  of  using  accumulators  in  large  mills  lies  in  the  fact  that  the  low- 
pressure  supply  can  be  utilised  for  working  the  meal-moulding  machines,  if  the  presses 
arc  of  the  Anglo-American  type,  the  hydraulic  cake-trimming  machines  referred  to 


THE  GENERAL  ARRANGEMENT  OF  OTL  :MTLLS 


79 


later  on  in  this  chapter,,  and  any  hydrauHc  lifts  with  wliich  the  mill  may  be  equipped. 
It  is  frequently  stated  that  a  still  furthei  advantage  attending  the  use  of  accumulators 
is  to  be  found  in  their  "  safety-valve  action,"  for  in  general  it  is  impossible  to  admit 
to  the  press  cylinder  and  its  connections  a  pressure  greater  than  that  for  which  the 
accumulatoi'  is  deliberately  loaded.  Tiie  implied  danger,  however,  need  be  no  greater 
with  a  properly  arranged  system  of  independent  pumps  than  it  is  with  accumulators. 

The  accumulators  used  in  oil  mills  are  in  no  essential  i-espect  diffei'ent  from  those 
used  for  other  purposes.  The  low-pressure  accumulator — see  Fig.  51 — may  be  loaded 
with  cast-iron  weights,  but  usually  it  is 
loaded  similarly  to  the  high-pressure 
accumulator  sho\\^l  also  in  Fig.  51, 
namely,  by  means  of  a  mild  steel  plated 
case  filled  with  slag,  sand,  or  other 
material.  The  cylinder  is  of  cast  iron, 
formed  externally  with  two  ribs,  on 
which  the  weight  case  is  guided.  The 
weights  are  hung  from  a  cast-iron  cross- 
head  fixed  to  the  top  of  the  ram. 
Sometimes  matters  are  reversed,  the 
ram  being  fixed  to  the  floor  and  tlie 
cylinder,  with  the  weight  case  attached 
to  it,  s'iding  on  the  ram. 

The  low-pressure  accumulators  are 
commmly  designed  for  a  pressure  of 
500  lb.  to  600  lb.  per  scpiare  inch. 
Their  rams  may  have  a  diameter  of 
from  8  in.  to  15  in.,  and  a  stroke  of 
from  8  ft.  to  12  ft.  The  high-pressure 
accumulators  give  a  working  pressure 
of  2  or  3  tons  per  square  inch,  accord- 
ing as  the  presses  are  of  the  Anglo- 
American  or  of  the  cage  type.  Their 
rams  varj'  in  diameter  from  2|-  in.  to 
5  in.,  and  in  stroke  from  5  ft.  to  12  ft. 
Li  Fig.  52  we  give  a  view  of  three 
accumulators  by  Manlove,  Alliott  &  Co.. 
Ltd.,  as  erected  in  an  oil  mill.  Here 
thei-e  are  two  low-pressure  accumulators,  each  with  a  stroke  of  lU  ft.,  and  one  high 
pressure  accumulator  with  a  stroke  of  5  ft. 


— Accumulator  I'liiiip — Maiilovo,  Alliott. 


Accumulator  Pumps. 
TJie  pumps  employed  in  coimection  with  the  accumulators  in  an  oil  mill  arc  usually 
of  a  vertical  reciprocating  belt-driven  type.  An  example  by  Manlove,  Alliott  &  Co., 
Ltd.,  is  illustrated  in  Fig.  53.  The  cast-iron  base  is  in  the  form  of  a  tank  into  which 
the  hydraulic  fluid  from  the  press  exhausts  and  from  which  the  pump  draws  its  supply. 
A  bridge  is  cast  acro.ss  the  top  of  the  tank,  and  on  this  are  fixed  the  side  frames  carrying 
the  driving  shaft.  The  side  frames  are  fixed  to  the  tank  by  means  of  bolts,  which 
extend  right  from  the  caps  of  the  driving  shaft  bearings  to  the  underside  of  the  bridge. 
The  driving  shaft  carries  an  excentric  at  each  end.  The  cxcentric  rods  arc  of  cast 
steel  and  each  reciprocates  a  crosshead  to  which  two  rams  are  attached.     The  rams 


80 


THE   PRODUCTION   AND  TREATMENT   OF   VEGETABLE   OILS 


work  within  forged  steel  blocks  fitted  into  the  top  of  the  tank.  The  suction  valves 
and  the  delivery  valves  are  fitted  with  renewable  seats  of  nickel  steel.  The  delivery 
valves  are,  as  shown  in  the  engraving,  arranged  in  two  steel  blocks  so  that  access 
may  readily  be  had  to  them.     The  chief  point  of  importance  to  pay  attention  to  in 

the  design  of  such  a  pump  as  this  is  the 
accessibihty  of  those  parts  liable  to  wear  or 
get  out  of  order.  Oil  mills  usually  are  run 
both  night  and  day,  so  that  any  repairs 
required  to  the  machinery  have  to  be 
effected  in  the  short  meal  time  stoppages. 

Accumulator  Relief  Valves. 

As  usual,  means  have  to  be  provided 
whereby  the  pumping  up  of  the  accumu- 
lators is  stopped  when  their  rams  reach  a 
certain  height.    Elsewhere  this  is  frequently 
effected  by  automatic   means    which    stop 
the    pumps.      Li  oil  mills,  however,  it    is 
customary   to    keep    the    pumps    running 
continuously  and,  when  required,  to  deflect 
tlieir  delivery  back  through  a  relief  valve 
into   the   supply   tank.     An  automatically 
worked  relief  valve  arrangement  by  Messrs. 
Manlove,  Alhott  is  illu.stratcd  in   Fig.  54. 
When  the  weight  case  of  the  accumulator 
reaches  its  prescribed  height,  a  bar  on  its 
crosshead,  shown  at  A  in  Fig.  52,  strikes 
the  end  of  the  lever  B  (Fig.  54),  and  pushes 
it  upwards.     The  opposite  end  of  this  lever 
is  connected  by  a  chain,  etc.,  in  the  manner 
shown  to  the  weighted  lever  of  the  relief 
valve.      This  lever  is  therefore  moved  up. 
It  is  held  up  by  the  action  of  the  cam  lever 
0  which,  moving  out  under  the  influence 
of  a  spring  plunger,  engages  the  pin  shown 
on    the   side   of   the   lever   B.      When  the 
accumulator  falls  again  the  bar  A  (Fig.  52) 
strikes    the    now  projecting  cam  lever  C, 
moves  it  in,  and  allows  the  weight  of  the 
lever  D  to  pull  down  the  lever  B  and  so 
resets  the  arrangement.     When  the  lever  D 
is   raised  the   delivery   from    the   pump    is 
deflected  from  the  accumulators  back  to  the  supply  tank.    When  the  lever  falls  again  the 
deUvery  to  the  accumulators  is  resumed.     The  actual  raising  of  the  weighted  lever  is 
not  effected  by  the  chain  and  rod,  but  by  a  plunger  beneath  it.      A  by-pass  supply 
of  low-pressure  fluid  is  admitted  beneath  this  plunger  by  a  piston  valve  E  operated 
when  the  lever  B  is  raised.     During  the  resetting  of  the  arrangement  this  piston  valve 
acts  as  a  dashpot  and  prevents  the  relief  valve  from  being  dropped  violently  on  to  its 
seating. 


Fig.  54 


-Belief  ^'alve  i)etaD8- 
.rUliott. 


Manluve, 


THE  GENERAL  ARRANGEMENT  OF  OIL  MILLS 


81 


Cake-trimming  Machines. 

Cake-trimming  machines,  as  will  have  been  gathered  from  what  has  already  been 
said,  form  quite  important  items  in  the  economy  of  oil  mills.  They  are  made  in  a 
variety  of  forms.  A  simple  arrangement 
for  paring  the  edges  of  straight-sided 
cakes,  made  by  Robert  Middleton  &  Co., 
is  shown  in  Fig.  55.  This  machine  is 
attended  by  two  youths  and  can  pare 
two  cakes  at  a  time.  It  comprises  two 
knives  moved  by  power  along  the  edges 
of  a  slot  at  the  centie  of  its  table.  The 
oily  parings  fall  into  the  slot,  where 
they  are  caught  in  a  trough  and  are 
broken  up  and  moved  forward  to  the 
spout  by  a  series  of  steel  conveyor  knives 
mounted  on  a  power-driven  shaft  within 
the  trough.  A  similar  type  of  machine 
is  made  by  Rose,  Do^vns  &  Thompson,  Ltd.,  except  that  all  the  driving  gear  is  carried 
on  two  standards  bolted  to  the  table  top,  the  idea  being  that  in  this  way  the 
woi"ldng  parts  camiot  become  clogged  with  oily  cake  parings.  A  machine  of  this 
type  is  indicated  in  the  mill  arrangement,  Fig.  47. 

Various  designs  of  automatic  cake-paring  machines  are  now  coming  into  use. 


The    Engineer"  ***"•    So 

Fig.  55. — Cake-Paring  Macbiue — Robert  Middleton. 


Fig.  56. — Hydraulic  Cake-Paring  Machine — Manlove,  Alliott. 

In  a  tjTjical  example  the  cakes,  one  by  one  from  a  pile,  are  moved  forward  against 
two  knives  set  at  the  desired  distance  apart.  Their  movement  is  then  continued  at 
right-angles  to  the  first  traverse,  so  that  the  two  remaining  edges  of  the  cakes  may  be 


82        THE   PRODUCTION  AND  TREATMENT   OF   VEGETABLE   OILS 

passed  between  a  second  pair  of  knives.     Such  a  macliine  can  readily  deal  with  thirteen 
cakes  per  minute. 

There  is  sometimes  a  Utile  difficulty  in  getting  a  clean-cut  edge  with  the  abofe 
machines.  Further,  their  operation  calls  for  a  certain  amoxmt  of  skill  and  judgment, 
and  the  cutting  knives  have  to  be  carefully  looked  after.  These  considerations  have 
led  to  the  introduction  of  hydraulic  parmg  machines.  An  example  of  this  class,  made 
by  Manlove,  Alliott  &  Co.,  Ltd.,  for  paring  the  roimd  cakes  obtained  from  cage  presses 
is  illustrated  in  Fig.  56.  In  this  machine  the  cakes,  one  at  a  time,  are  pushed  against 
stops  on  the  table  imdemeath  a  power-diiven  revolving  knife  having  saw-like  teeth. 
When  it  is  thus  in  position  pressure  is  admitted  to  a  hydi-aulic  cylinder  beneath  the 
table.  The  ram  head  forces  the  cake  against  the  revolving  knife,  which  trims  the 
cake  b\"  a  combined  shearmg  and  cutting  action.  The  cake,  after  being  trimmed, 
remains  within  the  circular  knife,  being  held  there  by  automatic  catches.  As  succeeding 
cakes  are  trimmed  the  pile  rises  into  the  hollow  top  of  the  macliine  until,  -with  each 
fresh  cake  fed  to  the  knife,  a  trimmed  cake  is  ready  to  be  removed  from  the  top  of 
the  pile.  Tiie  ram  is  conveniently  worked  from  the  low-pressure  accumulator,  but 
if  there  is  no  such  source  of  hydraulic  supply  the  machine  can  be  designed  to  utiUse 
steam  pressure.  Similar  machines  are  made  for  paring  Anglo-American  cakes.  In 
these,  of  course,  the  action  is  one  of  pure  shearing,  the  cakes  being  forced  up  against 
four  fixed  knives  arranged  at  the  edges  of  a  quadrilateral  opening  in  the  machine 
head. 


CHAPTER   XI 

EXTRACTION   OF   OILS   BY   CHEMICAL   SOLVENTS 

We  now  pass  on  to  describe  the  second  method  of  recovering  oils  from  vegetable 
substances,  namely,  their  extraction  by  means  of  chemical  solvents,  such  as  benzene, 
ether,  chloroform,  carbon  disulphide,  carbon  tetrachloride — CCI4 — and  tetrachlore- 
thane — C2CI4H2.  The  idea  of  using  solvents  for  this  purpose  is  by  no  means  a  recent 
one.  It  was  introduced  as  a  practical  process  as  long  ago  as  1843,  by  Fisher, 
of  Birmingham.  It  is,  nevertheless,  true  that  only  recentlj^  has  the  process  come 
to  be  extensively  adopted,  for  it  has  had  to  struggle  against  the  prejudices  inherited 
from  its  earlier  and  admittedly  impeifect  working.  These  prejudices  are  not  yet  by 
any  means  dead,  and  even  in  text-books  of  high  standing  statements  are  to  be  found 
concerning  the  results  of  the  process  which  seem  to  be  based  on  misinformation  as  to 
its  modern  state  of  development. 

Objections  Alleged  Against  the  Process. 

Before  proceeding  to  describe  modern  examples  of  solvent  extraction  plant  it  is 
very  desirable  that  we  should  deal  with  tlie  objections  which  have  been  and  still  are, 
urged  against  the  process.  We  may  preface  our  remarks  under  this  head  by  saying 
that  in  brief  the  process  consists  of  allowing  one  of  the  solvents  named  above  to  perco- 
late through  the  seed  or  meal  in  a  closed  vessel,  heated  or  cold,  of  draining  off  the  solvent 
and  the  oil  which  it  has  dissolved  from  the  seed,  of  transferring  the  liquid  to  a  heated 
still,  and  of  then  driving  off  the  volatile  solvent  so  as  to  leave  the  oil  behind.  The 
solvent  driven  off  is  condensed  and  used  repeatedly. 

The  objections  alleged  against  the  process  fall  into  three  principal  categories. 
In  the  fir.st  place  it  is  argued  that  it  extracts  the  oil  so  effectively  from  the  seed  that 
the  residue  of  meal  is  next  to  useless  as  a  cattle  food  and,  at  best,  is  fit  only  for  manure. 
Secondly,  it  is  stated  that  it  is  difficult  or  impossible  entirely  to  eliminate  all  trace 
of  the  solvent  used  both  from  the  oil  and  the  residue  of  meal,  so  that  the  oil  is  made 
unfit  for  edible  purposes  and  fit  only  for  soap-making  and  kindred  uses,  while  the 
nauseous  taste  or  poisonous  action  of  the  .solvent  left  in  the  meal  provides  a  second 
reason  why  such  meal  should  not  be  fed  to  cattle.  In  the  third  place,  not  one  of  the 
solvents  used,  it  is  .said,  is  free  from  technical  objections.  Thus  ether  and  chloroform 
are  far  too  expensive  to  permit  of  their  use  commercially.  This  .seems  to  be  a  sound 
contention.  Carbon  tetrachloride,  it  is  urged,  is  aLso  expensive  and  is  apt  to  exercise 
a  poisonous  action  on  the  workers  attending  the  recovery  plant.  Further,  while 
admittedly  non-inflammable,  it  suffers  from  the  great  disadvantage  that  it  very 
readily  attacks  metals.  Regarding  carbon  disulphide,  it  is  argued  that  while  it  is 
a  very  good  solvent  it  is  difficult  to  obtain  pure  and  that  it  is  apt  to  impart  even  to 
soap  made  from  oil  extracted  with  it  an  unpleasant  sulphurous  smell.  It  is  further 
very  readily  inflammable,  and,  like  carbon  tetrachloride,  exercises  a  poisonous  action 
on  those  working  with  it.  Again.st  benzene  the  chief  objection  levelled  is  its  inflam- 
mability. In  addition  it  is  stated  to  be  the  most  difficult  of  all  the  solvents  to  eliminate 
from  the  oil  and  meal.  Tetrachlorethane  is  a  solvent  of  recent  introduction.  So  far 
as  we  know  it  is  not  as  yet  in  extensive  use  for  the  extraction  of  oils.     It  seems,  however, 


84         THE   PRODUCTION  AXD   TREATMENT   OF   VEGETABLE   OILS 

to  possess  certain  features  which  may  in  time  lead  to  its  wide  adoption.  Thus,  its 
commercial  production  appeais  to  be  simpler  than  that  of  carbon  tetrachloride,  while 
its  action  on  metals  is  much  less. 

It  must  be  admitted  that  certain  of  the  above-mentioned  objections  are  perfect'y 
sound  when  applied  to  the  process  as  carried  out  with  old-fashioned  apparatus — 
frequently  of  German  origin — and  using  carbon  disulphide  as  the  solvent.  As  applied 
to  modem  British -made  plant  using  benzene,  as  in  the  case  of  the  system  to  be  described, 
they  appear  to  be  quite  out  of  date  and  in  direct  conflict  with  established  fact.  It  is 
undoubtedly  true  that  the  process,  as  it  can  now  be  carried  out,  is  rapidly  being  adopted 
on  an  extensive  scale,  a  circumstance  which  seems  to  afford  conclusive  evidence  that 
the  objections  summarised  above  are  now  recognised  as  being  no  longer  vaUd. 

The  Objections  Refuted. 

In  refutation  of  the  objections  urged  against  the  process  it  may  Ije  directly  stat-ed 
that  extracted  meals  are  daily  being  used  in  large  quantities  both  in  this  country  and 
abroad  as  food  for  cattle,  while  a  mimljer  of  plants  are  at  work  in  tliis  country  using 
the  chemical  solvent  extraction  process  and  producing  nothing  but  oil  of  edible  quality, 
as,  for  instance,  oils  which  are  used  in  the  manufacture  of  first-grade  margarine.  Here 
we  have  evidence  that  all  traces  of  the  solvent  used  can  now  be  ehminated,  both  from 
the  oil  and  the  meal.  Whether  or  not  the  entire  absence  of  oil  in  extracted  meal  lowers 
the  value  of  the  residue  as  a  foodstuff  is  a  very  debatable  point.  There  are  distinct 
indications  that  a  marked  percentage  of  oil  in  a  cattle  food  is  not  quite  as  great  an 
advantage  as  it  was  at  one  time  beheved  to  Ije.  This  seems  to  be  recognised  by  many 
cattle-feeders  themselves  and  is  supported  by  the  views  expressed  in  the  recent  report 
of  the  Government  Committee  on  Oil  Seeds,  which  views  tend  to  the  recommendation 
as  a  cattle  food  of  extracted  meal  even  when  next  to  entirely  free  from  oil.  In  explana- 
tion of  this  it  may  be  pointed  out  that  while  oil  is  a  heat  former  it  is  the  albumenoids 
in  the  material  that  count  from  the  actual  food  or  flesh -forming  point  of  view,  and 
that  extracted  meal  is  richer  in  these  albumenoids  than  the  cake  procured  by  pressing 
the  same  seeds. 

Apart  from  this  question  it  is  to  be  noted  that  no  oil  cake  is  fed  by  itself  to  cattle. 
It  is  diluted  with  bran  or  other  substance.  The  "  other  substance  "'  may  very  well 
be  extracted  meal,  which  may  l>e  mixed  with  the  cake  to  give  a  foodstuff  of  the  desired 
oil  content.  In  any  event  the  argmnent  against  the  extraction  process,  which  is 
based  on  the  deficiency  of  oil  in  the  residue,  entirely  falls  to  the  ground  when  we 
observe  that  under  modem  conditions  the  operator  using  this  process  can  arrange 
to  leave  as  much  or  as  little  oil  in  the  residue  as  he  may  desire. 

Advantages  of  the  Pkocess. 
From  the  technical  point  of  view  the  chief  advantages  attending  the  adoption 
of  the  process  he  fii'st  in  the  comparative  simphcity  and  cheapness  of  the  plant  required  ; 
secondly,  in  the  small  amovmt  of  power  absorbed  ia  driving  the  plant  ;  and  thirdly, 
in  the  fact  that  the  labour  demanded  for  its  attendance  need  not  be  highly  skilled. 
From  the  commercial  point  of  view  its  full  advantages  can  otdy  be  assessed  by  a 
careful  study  of  certain  factors  which  vary  from  place  to  place  and  from  time  to  time. 
If  it  be  a  question  whether  the  press  or  extraction  system  shall  be  adopted,  everything 
turns  upon  whether  or  not  the  seed  to  be  treated  yields  a  residue  which,  quite  apart 
from  the  process  of  recovery  used,  is  in  demand  as  a  cattle  food.  Thus  rape  seed, 
even  when  treated  by  the  crushing  process,  is  not  greatly  valued  as  a  cattle  food.  In 
such  cases  the  only  product  primarily  to  be  considered  is  the  oil.     This  naturally 


EXTRACTION    OF    OILS    BY    CHEMICAL   SOLVENTS  85 

points  to  the  adoption  of  the  solvent  extraction  process  as  the  better  method  of  treating 
such  material  in  view  of  the  considerably  higher  yield  of  oil  which  it  secures.  A 
secondary  consideration  points  in  the  same  direction.  If  the  residue  of  the  seed  is 
unsuitable  as  a  cattle  food,  its  only  other  important  outlet  is  as  a  manure  or  fertiliser. 
Press  cake  has  to  be  broken  up  and  reduced  again  to  meal  before  it  can  be  used  for 
this  purpose.  Extracted  meal  is  suitable  for  it  as  soon  as  it  is  taken  out  of  the  extractor 
plant.  Far  more  important  than  this,  however,  is  the  fact,  now  well  established,  that 
grease  or  oil  in  a  fertiliser  prevents  the  soil  foods  from  being  absorbed  by  the  soil  for, 
if  present,  it  acts  to  defend  the  fertihser  against  the  attacks  of  those  organisms  which 
convert  the  constituents  of  the  fertiliser  into  immediate  soil  foods.  Clearly,  then, 
the  extraction  process,  ehminating  as  it  can  be  made  to  do  practically  all  oil  from  the 
residue,  has  very  great  claims  to  attention  when  the  residue  has  to  be  used  as  a  fertiliser. 
If  the  seed  residue,  on  the  other  hand,  is  suitable  for  cattle-feeding  purposes,  the 
first  point  to  consider  is  whether  there  is  a  local  market  for  it  in  this  form.  It  may  well 
be  that  there  is  not,  and  that,  in  view  of  the  cost  of  shipping  the  residue  to  the  nearest 
market,  the  balance  is  in  favour  of  using  the  residue  as  a  manure.  Here  again  the 
adoption  of  the  solvent  extraction  process  is  indicated  as  desirable.  The  conditions 
here  touched  upon  arise  very  often  when  the  recovery  of  the  oil  in  the  neighbourhood 
where  the  oil-bearing  seed  is  grown  is  under  consideration.  This  practice  is  desirable 
in  itself,  for  the  seed,  being  fresh,  will  almost  certainly  produce  a  better  oil  than  it 
would  after  deteriorating  during  its  journey  to  some  distant  factory.  There  is,  however, 
probably  no  local  or  conveniently  adjacent  market  for  the  residue  as  a  cattle  food, 
and  this,  up  to  the  present,  has  led  to  the  shipping  of  enormous  quantities  of  oil-bearing 
seed  for  treatment  in  this  and  other  countries  remote  from  the  country  growing  the 
seed.  By  adopting  the  solvent  extraction  process  the  grower  can  save  freight  charges 
by  shipping  nothing  but  oil,  and  can  dispose  satisfactorily  of  the  residue  by  using  it 
as  a  manure  on  his  own  plantations. 

Commercial  Aspect  of  the  Process. 

We  thus  see  that  the  solvent  extraction  process  has  distinct  claims  to  attention 
when  : 

(a)  The  residue  is  not  usable  as  a  cattle  food  by  reason  of  the  nature  of  the  seed 
itself,  and  when 

(6)  The  residue,  although  suitable  for  cattle  feeding,  is  not  u.sable  in  this  way 
by  reason  of  there  being  no  market  for  it  situated  conveniently  near  the  mill.  A  third 
case  arises,  namely,  when 

(c)  The  residue  is  usable  as  a  cattle  food,  and  can  be  conveniently  disposed  of 
as  such.  The.se  conditions  are  met  with,  for  example,  when  it  is  a  question  of  treating 
linseed  or  cotton  seed  in  this  country. 

Which  process  it  is  best  to  adopt  under  these  circumstances  is  a  matter  for  very 
close  study.  Several  factors  are  involved.  But  in  investigating  the  matter  a  certain 
line  of  argument  frequently  advanced  by  tho.se  interested  in  the  solvent  extraction 
process  should  not  be  too  readily  accepted.  According  to  this  argument  it  is  poor 
policy  to  dispose  of  oil  as  a  constituent  of  oil  cake  fetching  £12  to  £18  per  ton,  when, 
by  extracting  it  completely,  it  can  be  sold  for  £40  to  £60  per  ton.  This  argument 
appears  to  be  fallacious,  in  so  far  as  it  overlooks  the  fact  that  it  is  the  custom  of  the 
oil-seed-crushing  industry  to  charge  for  the  oil  cake  in  such  a  way  that  the  oil  in  it 
reaps  the  same  price    as  the  bulk  of  the  oil  separated  from   the  seed.      Thus   a 


86         THE   PRODUCTION   AND  TREATMENT   OF   VEGETABLE   OILS 

ton  of  linseed  containing  40  per  cent,  of  oil  originally,  after  being  crushed,  appears 

roughly  as — 

£    i.    d. 
747  Ih.  oil :  value,  at  £o3  per  ton        ..  ..  ..17134 

1,493  lb.  cake  :  value,  at  £19  per  ton 12  13    4 


2,240  30  6  8 
Cake :  1 0  per  cent.  oiL 

149  lb.  oil :  value,  at  £53  per  ton                               3  10  8 

1,344  lb.  dry  residue :  value,  at  £15  4s.  bii.  per  ton  . .                              9  2  8 


Similarly,  a  ton  of  undecorticated  Egyptian  cotton  seed  containing  24  per  cent.  »)t 

oil  originally  wiU,  after  crashing,  appear  as — 

£    s.    ./. 

a4S  lb.  oil :  value,  at  £53  per  ton        . .       8    4  11 

1.S92  lb.  rake:  value,  at  £15  10s.  per  ton        13     1     9 

2,240  21  6  10 
Cake  :  10  per  cent.  oil. 

189  lb.  oil :  value,  at  £53  per  ton        4  U  4 

1,703  lb.  dry  residue  :  value,  at  £1 1  7s.  per  ton  8  12  5 

1.892  13     1     9 

Clearly,  then,  so  far  as  the  money  reahsed  hyhis  products  is  concerned,  it  does  no( 
matter  to  the  oil  crusher  how  much  or  bow  Httle  oil  he  leaves  behind  in  his  cakes 
He  gets  the  same  price  for  the  oil  whether  he  recovers  it  or  allows  it  to  remain  in  tlie 
cake.  Were  he  to  adopt  the  solvent  extraction  process  he  would  not  reahse  a  penny 
more  for  the  oil  contained  originally  in  the  seed. 

At  the  present  moment  in  this  country  linseed  and  cotton  seed  are  crushed  rather 
than  extracted,  because  a  demand  exists  for  linseed  and  cotton  seed  press  cake  contain- 
ing a  considerable  percentage  of  oil.  Rightly  or  wrongly,  little  or  no  demand  exists 
for  linseed  and  cotton  seed  extracted  meal.  On  the  other  hand,  rape  seed  is  extra.cted 
rather  than  cnished,  because  no  demand  exists  for  rape  seed  press  cake.  The  oil 
left  in  such  cake  would  represent  a  sheer  loss,  for  the  cake  could  not  be  sold  at  a  highei 
figure  than  the  extracted  meal.  In  addition,  the  oU  left  in  the  cake  would,  as  we  have 
already  stated,  lower  the  manurial  value  of  the  residue. 

By  way  of  conclusion  to  this  brief  discussion  of  the  relative  merits  of  the  two 
processes,  we  need  only  remark  that  they  should  not  Ije  regarded  necessarily  as  rivals. 
The  solvent  extraction  process  has  a  very  distinct  field  of  its  own.  Worked  side  by 
side  with  the  crushing  process,  so  as  to  recover  the  last  portion  of  oil  from  the  seed, 
it  is  of  veiy  great  value  in  ceitain  particular  cases,  as,  for  example,  when  the  material 
to  \ye  treated  is  olives.  As  a  direct  alternative  to  crushing  its  importance  is  rapidly 
increasing.  When  the  true  value  of  extracted  meal  as  a  cattle-feeding  stuff  l^ecomes 
more  generally  recognised  the  rivaln,-  of  the  process  with  the  crushing  method  will  no 
doubt  tmdergo  great  development. 

The  Ideal  or  the  Process. 

The  ideal  solvent  extraction  process,  it  can  be  said,  should  seem*  the  complete 
recovery  of  all  the  oil  in  the  seed — or  as  much  of  it  as  it  is  desired  to  recover — in  one 
stage,  and  should  leave  the  residue  of  the  seed  in  a  drj"  state.  It  may  be  remarked 
that  certain  extraction  processes  fall  short  of  this  ideal,  in  so  far  as  the  meal  after 
extraction  has  to  be  separately  dried. 


INSERT  FOLDOUT  HERE 


EXTRACTION    OF    OILS    BY    CHEMICAL    SOLVENTS  87 

Preparation  of  the  Material. 
Palm  kernels,  copra,  soya  beans,  and  similar  materials  are  prepared  for  tbe  extrac- 
tion process  in  precisely  the  same  Avay  as  for  crushing,  the  only  difference  being  that 
the  flesh  need  not  be  reduced  or  shredded  to  quite  the  same  degree  of  fineness.  Seeds 
such  as  rape  seed,  linseed,  etc.,  need  only  be  lightly  rolled.  Cotton  seed,  castor  seed 
beans,  and  similar  material  commonly  decorticated  before  being  ciushed  can,  if  desired, 
be  extracted  in  an  undecorticated  state,  the  seed  being  simply  rolled  so  as  to  break  the 
cortex.  The  saving  of  the  expense  of  decorticating  results  in  considerable  economy 
if  the  residue  is  to  be  used  as  a  fertiliser,  or  if  the  skin  or  shell  of  the  seed  being  treated 
possesses,  as  is  sometimes  the  case,  a  distinct  feeding  value. 

The    "Scott"  Extraction  Plant. 

One  of  the  best-known  forms  of  solvent  extraction  plant  is  that  working  on  the 
"  Scott  "  system,  and  made  by  George  Scott  &  Son  (London),  Ltd.,  Kingsway  House, 
Kingsway,  London,  W.C.     LTnder  this  system  the  solvent  commonly  used  is  benzene. 

Benzene — or  benzol,  as  it  is  stiU  frequently  called  in  commerce — is,  when  pure, 
a  colourless  liquid  having  a  specific  gravity  of  about  088  at  15°  C,  and  boiling  under 
normal  pressure  at  about  80°  C.  It  is  very  slightly  soluble  in  water,  but  is  soluble  .n 
alcohol,  ether,  carbon  disulphide,  etc.  On  the  other  hand,  it  very  readily  dissolves 
resins,  sulphur,  phosphorus,  fats,  oils,  and  many  alkaloids,  and  other  organic 
compounds. 

Two  features  of  the  "  Scott  "  system  may  here  be  set  down.  In  the  first  place, 
the  extraction  is  performed  in  the  cold,  thereby  practically  eliminating  all  dangei 
arising  from  the  inflammable  nature  of  the  solvent  used.  Secondly,  the  extraction 
is  effected  partly  by  the  solvent  in  liquid  form  and  partly  by  it  in  the  form  of  a  vapour. 
In  this  respect,  the  system  differs  from  others.  In  general  the  solvent  is  wholly  in 
tiie  form  of  a  liquid,  although  it  is  evident  that  when  hot  extraction  is  adopted  the 
solvent  admitted  as  a  liquid  must  at  least  in  part  become  vaporised.  The  "  Scott  " 
system,  therefore,  may  be  said  to  combine  the  advantages  of  hot  extraction  with  the 
safety  of  cold  extraction. 

In  Plate  V.  we  reproduce  a  drawing,  specially  prepared  for  us  by  Messrs.  Scott, 
showing  in  diagrammatic  form  the  plant  used  under  the  "  Scott  '"  system.  Figs.  57, 
58  and  59  show  views  of  actual  installations,  while  in  Fig.  60  a  small  extraction  plant 
suitable  for  trial  and  similar  purposes  is  represented.  Referring  to  the  line  engraving 
it  will  be  seen  that  each  extractor  is  fed  with  meal  through  a  door  at  the  top  from  an 
overhead  hopper.  The  doors  are,  as  indicated  in  Fig.  58,  provided  with  hinged  bolts, 
so  that  they  may,  when  the  extractor  is  charged,  be  readily  and  tightly  fastened  down. 
The  hopper  system  of  feeding  the  extractors  economises  labour,  but  entails  the  erection 
of  a  fairly  lieavy  superstructure.  In  large  mills  it  is  sometimes  foui.d  conven  ent  to 
dispense  with  hoppers  and  to  provide  instead  a  conveyor  with  a  suitable  oil-take  to 
each  extractor.  This  method  has  an  additional  advantage  over  the  hopper  system, 
in  that  by  its  adoption  it  is  readily  possible  to  feed  the  extractors  with  a  mixture  of 
seeds  in  any  required  proportion. 

With  many  materials  it  is  desirable  that  the  mass  in  the  extractor  should  be 
agitated  while  the  solvent  is  at  work.  Figs.  57  and  58  and  the  diagram  represent 
plants  pro\ided  with  agitating  gear  driven  by  means  of  a  belt  prdley,  worm  and  worm 
wheel.  The  plant  shown  in  Fig.  59  has  no  agitator.  When  the  extraction  process 
is  completed    the  discharge  doors  near  the  foot  of  the  extractors  are  opened  so  that 


88        THE  PRODUCTION  AND  TREA-mENT  OF  ^'EGETABLE  OILS 

the  agitator  may  deliver  the  residue  of  the  meal  on  to  a  conveyor  which  runs  past 
the  doors.  This  residue,  it  is  to  be  noted,  is,  under  the  "  Scott '"  method  of  working, 
quite  dry  and  can,  if  required,  be  fed  directly  to  cattle  or  horses,  if  the  seed  being 
treated  renders  this  practicable. 

Gen'eeal  ^Method  or  Wobkixg. 
During  the  period  of  extraction,  the  solvent,  with  the  oil  it  ha*  dissolved,  is  drained 
off  from  the  foot  of  the  extractor  through  the  pipe  A.     Passing  along  the  pipe  B  it 
reaches  a  stream -heated  tubular  vaporiser.     Here  a  portion  of  the  solvent  is  driven 


Fig.  57. — Benzene  Solvent  Extraction  Plant — Scott. 

off  as  vapour,  and  rising  up  the  pipe  C  this  portion  enters  the  extractor  at  the  top  to 
act,  as  we  have  explained,  in  conjunction  with  the  solvent  admitted  as  a  liquid.  The 
remaining  portion  of  the  solvent  with  all  the  dissolved  oil  leaves  the  foot  of  the  vaporiser 
at  D,  and  ilowing  along  the  pipe  E  reaches  a  pump  which  lifts  it  up  into  a  stUl-feed 
tank.  Leaving  this  by  way  of  the  pipe  F  the  liquid  flows  through  a  heater-condenser — 
or  "  heat  exchanger "" — and  so  reaches  the  continuous  still,  appearing  Hke  a  column 
on  the  right  of  the  engraving. 

The  construction  of  this  still  will  be  referred  to  shortly.  For  the  time  being  it 
is  sufficient  to  say  that  it  completely  drives  off  the  solvent  from  the  oil.  The  finished 
oil  leaves  the  still  at  the  foot  as  indicated.  The  solvent  vapour  finds  its  exit  at  the 
top  through  the  pipe  G.  Flowing  through  the  heater-condenser  it  is  partially  con- 
densed by  the  contra-flowing  liquid  passing  to  the  still,  and,  at  the  same  time,  assists 
the  work  of  the  still  by  pre-heating  the  incoming  supply  of  liquid.     Leaving  the 


EXTRACTION    OF    OILS    BY   CHEMICAL   SOLVENTS 


80 


Fio.  58. — Scott  Solvent  Extractor  with  Asitatinj?  Gear. 


Il^fcl^^w^ 

f          ^ 

] 

Lj  na^s 

^^^>i 

■Ir^^ 

1                 -     ^^ 

'^^^Wi^  V 

l-'io.  .')9.— Siutt  S,,lviiit  Extnietor  without  A-ita 


Itatlli'-  Ij.j.ll. 


90 


THE  PRODUCTION  AND  TREATMENT  OF  VEGETABLE   OILS 


heatei'  condenser  the  partially  condensed  solvent  vapour  is  reduced  completely  to 
liquid  in  two  condensers.  On  the  way  through  the  still,  as  we  shall  see  presently,  it 
has  picked  up  some  water.  It  is,  therefore,  taken  by  way  of  the  pipe  H  to  a  water 
separator.  The  action  of  this  separator  depends  upon  the  difference  between  the 
specific  gravities  of  the  solvent  and  water.  The  water  flows  off  at  the  pipe  J.  The 
liquid  solvent  passes  along  the  pipe  K  into  a  store  tank  ready  for  re-use. 

It  will  thus  be  seen  that  of  a  given  amount  of  solvent  introduced  into  the  extractor 

a  portion  is  returned  directly  to  the 
extractor  as  vapour,  and  a  portion  is 
delivered  into  the  store  tank  ready  for 
re-use.  The  former  portion  emerging 
from  the  extractor  as  liquid  containing 
oil  in  solution  again  reaches  the 
vaporiser.  Part  of  it  is  returned  once 
more  as  vapour  to  the  extractor,  and 
the  remainder,  passing  through  the 
still,  is  cleaned  of  dissolved  oil  and 
joins  the  first  portion  of  the  original 
charge  of  solvent  in  the  store  tank. 
Obviously,  as  time  goes  on,  rmless 
something  is  done,  practically  all  the 
original  charge  of  solvent  will  be  found 
in  the  store  tank  ;  no  vapour  worth 
speaking  of  \nll  be  foimd  ascending  the 
pipe  C,  and  the  extraction  process  will 
come  automatically  to  a  standstill. 

This  condition  may  or  may  not 
correspond  \^ith  the  complete  recovery 
of  the  oil  from  the  seed  or  with  the 
degree  of  recoveiy  desired.  If  it  does 
not,  a  fresh  quantitj'  of  clean  solvent  is 
passed  into  the  extractor  to  complete 
the  process  or  carry  it  a  stage  further. 
The  maimer  in  which  this  fresh  cpiantity 
is  introduced  is  the  same  as  that  in 
which  the  original  amount  of  solvent  is 
admitted  into  the  extractor  at  starting 
up.  It  is  conducted  as  foUows  : — The 
workman  temporarily  closes  the  valve  L  and  opens  the  valves  M  and  X.  Clean 
solvent  from  the  store  tank  now  flows  down  the  pipe  P  to  the  vaporiser.  Partly  as 
vapour  it  rises  up  the  pipe  C  to  the  extractor,  and  partlj'  as  Uquid  it  flows  out  at  D  to 
the  pump  which,  lifting  it,  sends  it  along  the  pipe  Q  past  the  valve  X  into  the 
extractor  at  R.  When  sufficient  fresh  solvent  has  thus  been  introduced,  the  valves 
are  reset  and  the  former  process  is  resumed. 

It  is  found  that  when  the  extraction  of  the  oil  from  the  meal  is  nearlj-  completed, 
the  solvent  drawn  off  from  the  extractor  contains  very  little  oil.  It  is  not  economical 
to  pass  this  poor  liquid  into  the  still.  It  is  therefore  sent  into  a  '  half-spent  '  solvent 
tank — not  shown  in  the  diagram — and  is  re-used  as  the  first  charge  of  solvent  for  a 
fresh  charge  of  meal. 


-Small  Solvent  I'laut. 


EXTRACTION    OF    OILS    BY    CHEMICAL    SOLVENTS  91 

Cleaning  the  Meal  of  Solvent. 

When  the  exti'action  is  quite  completed,  and  before  the  discharge  doors  are 
opened,  the  valves  L  and  S  are  shut  dowii  and  the  valve  T  is  opened.  Steam,  in  a 
dry  condition  but  not  supei'heated,  is  then  admitted  to  the  extractor  through  the  valve 
U.  Blo\\'ing  through  the  meal  this  steam  carries  off  all  traces  of  tlie  solvent  from  the 
meal.  The  steam  and  solvent  vapour  rising  up  the  pipe  V  reach  the  condensers, 
and  traversing  the  water  separator  as  before,  are  passed  respectively  to  waste  and  to 
the  store  tank. 

Alternative  Method  of  Working. 

The  above  description  relates  to  the  M'orking  of  one  extractor.  The  other  extractor 
is  worked  similarly,  the  vaporiser  and  its  connecting  piping  being  duplicated  for  this 
purpose.  Our  description,  further,  covers  only  one  method  of  working  the  plant. 
Modifications  are  provided  for.  Thus  the  vaporiser,  once  the  original  charge  of  solvent 
has  been  introduced  into  the  extractor,  can  be  completely  cut  out,  so  that  the  extraction 
may  be  performed  entirely  by  liquid  solvent.  To  achieve  this  the  valve  L  is  held 
closed  and  the  valves  W  and  the  valve  N  opened.  The  solvent,  with  its  dissolved  oil 
now  reaches  the  pmnp  without  passing  through  the  vaporiser,  and  is  sent  back  to  the 
extractor  along  the  pipe  Q.  After  it  has  been  circulated  through  the  meal  a  sufficient 
number  of  times  it  is  sent  into  the  still  feed  tank  by  closing  the  valve  N. 

Safety  Valves. 
With  ))lant  of  tliis  nature  it  is  very  important  to  provide  safety  valves  at  all  points 
where  pressure  might  coneeivably  accumulate,  and  at  the  same  time  to  provide  means 
whereby  this  pressure  may  be  relieved  without  allowing  any  of  the  inflammable  solvent 
vapour  to  escape  into  the  atmosphere.  The  points  at  which  excess  pressure  might 
possibly  accumulate  are  in  the  vaporisers,  in  the  extractors,  and  in  the  still.  Safety 
valves  are  therefore  provided  at  X,  Y,  and  Z,  respectively.  It  will  be  noticed  that 
the  two  safety  valves  X  are  connected  by  a  horizontal  pipe  having  union  with  the 
pipe  V,  up  wliich  the  cleaning  steam  passes  at  the  termination  of  tiie  extraction  process. 
Excess  vapour  passing  the  safety  valves  X  does  not  escape  into  the  atmosphere,  but 
into  this  horizontal  pipe,  and  so  reaches  the  condensers.  A  similar  arrangement  is 
provided  for  the  safety  valves  Y.  The  safety  valve  Z  for  a  similar  reason  is  arranged 
on  a  by-pass  bridging  the  stop  valve  for  the  still,  and  delivers  any  excess  vapour 
e.scaping  past  it  through  the  heater-condenser  into  the  main  condensers.  There  is 
little  danger  of  any  accumulation  of  pressure  within  the  conden.sers  or  store  tank. 
But,  in  any  event,  the  water  separator  acts  as  a  seal  to  both,  and  therefore  as  an 
emergency  pressure-relieving  device.  On  the  top  of  each  vapour  pipe  C  a  deadweight 
safety  valve  is  provided  with  outlet  direct  to  the  atmosphere.  This  is  a  purely  precau- 
tionary measure.  The  valve  is  .set  to  a  few  pounds  above  the  release  pressure  of  the 
valve  X,  and  is  intended  to  come  into  use  should  the  latter  valve,  for  any  rea.son,  fail 
to  act.  So  far  as  Messrs.  Scott  know  these  deadweight  safety  valves  have  never  yet 
on  any  of  their  plants  been  called  upon  to  fulfil  their  function. 

The  Continuous  Still. 
The  separation  of  the  solvent  from  the  oil  is  begun  in  the  vapox'iser.  This  is  done 
simply  to  take  incidental  advantage  of  the  steam  required  to  generate  the  vapour  for 
the  extractor.  The  main  and  final  separation  takes  place  in  the  still.  This  separation 
is  a  most  important  feature  of  the  process,  for  on  its  completeness  must  largely  depend 
the  commercial  value  of  the  oil  recovered.     Very  frequently  this  separation  has  been 


92        THE  PRODUCTION  AND  TREATMENT  OE  \rEGETABLE   OILS 

attempted  in  stills  of  the  pot  or  bulk  charge  type.  This  naethod  of  working  occupies 
a  considerable  amount  of  time,  a  fact  imjiortant  in  itself  and  also  in  its  bearing  upon 
the  effect  which  contact  with  heat  for  a  prolonged  period  has  upon  most  oils.  Li 
addition,  towards  the  end  of  the  operation  there  is  little  solvent  to  remove,  so  that 
during  this  time  the  steam  used  to  drive  off  the  solvent  cannot  be  used  with  full 
efficiency.  Thus  fuel  is  wasted,  and  an  unnecessary  tax  is  placed  on  the  condensers 
which  collect  the  steam  and  solvent  vapour. 

The  still  shown  in  the  diagram  is  of  a  form  recently  patented  by  Mcs.srs.  Scott. 
A  number  of  these  stills  are  already  satisfactorily  at  work  on  the  production  both  of 
edible  and  of  trade  oils.  The  "  Scott  "  still  is  divided  into  a  number  of  sections, 
each  of  which  is  a  still  by  itself.  The  oil  and  solvent  mixture  heated  in  the  "  heater- 
condenser  "  to  approximateh'  the  distilling  temperature  enters  the  top  section  of  the 
still  and  passes  downwaids  in  turn  through  each  of  tlie  others.  In  so  doing  it  comes 
into  direct  contact  with  an  ascending  current  of  steam  admitted  below  the  bottom 
section  of  the  still  and  bafHed  in  such  a  way  as  to  cause  it  to  take  a  tortuous  course 
through  the  descending  Uquid.  As  the  steam  ri.ses  it  liberates  the  solvent  as  vapour, 
which  vapour  assists  the  steam  in  distilling  the  solvent  from  the  liquid  passing  through 
the  next  liighest  section  of  the  still.  It  will  be  seen  that  under  thi.s  method  of  worldng 
the  freshest  steam  is  caused  to  act  upon  the  liquid  with  the  least  amount  of  solvent  in 
it,  that  is  to  say,  in  the  liquid  at  the  time  when  it  contains  those  last  traces  of  solvent 
which  are  the  most  difficult  to  remove.  At  the  top  of  the  still  the  steam,  partially 
used  up,  is  given  the  easiest  work  to  do,  namely  to  attack  the  liquid  when  it  is  richest 
in  solvent,  and  therefore  has  tlie  lowest  boiling-point. 

Working  Charges. 

It  is  claimed  for  the  "  Scott  "  system  that  verj'  little  labour  is  required  to  run  the 
plant.  The  pioportion  which  the  labour  charges  will  bear  to  the  other  working  costs 
depends,  however,  on  the  size  of  the  plant,  for  while  the  size  varies,  the  number  of 
men  required  to  operate  it  remains  constant.  It  is  stated  that  the  vexy  largest  plants 
consisting  of  many  extractors  can  be  operated  by  two  men.  Economy  of  steam 
consumption  is  another  pouit  connected  with  the  plant  to  which  the  makers  call 
attention.  The  coal  required  per  ton  of  raw  material,  we  are  hiformed,  may  be  set 
down  as  from  2  to  3  cwt.  The  only  other  item  of  working  costs  to  be  considered 
relates  to  the  solvent.  It  is  fomid  that  in  operation  a  certain  amount  of  solvent 
disappears  ;  where  it  goes  to  is  by  no  means  clear.  This  loss  may  be  returned  at 
Ig  gallons  per  ton  of  material  treated. 

It  is,  perhaps,  worth  adding  that  the  solvent  extraction  process  has  to-day  a 
very  wide  field  of  application  outside  of  the  vegetable  oil  industr}\  It  is  bemg 
employed  for  the  extraction  or  recovery  of  grease,  oil,  or  fat,  from  many  miscellaneous 
substances,  such  as  wool  waste,  bones,  leather  scrap,  rags,  factory  sweepings,  and 
refuse  of  all  sorts. 


CHAPTEK   XII 
THE   REFINING   OF   OILS 

We  now  come  to  a  section  of  our  subject  concerning  wliich  a  great  deal  of  secrecy 
is  commonly  exercised.  Oil  refining  is  usually  carried  out  in  works  quite  separate 
from  the  mills  producing  the  oil.  It  may,  in  fact,  be  properly  regarded  as  constituting 
an  industry  by  itself.  It  requires  the  possession  of  a  considerable  laiowledge  of 
chemistry,  for  each  oil  in  general  has  to  be  treated  in  a  special  manner.  The  refining 
may  be  carried  out  to  vaiying  degi'ees  of  completeness.  According  to  its  degree,  so 
does  the  enhanced  price  obtained  for  the  oil  vary.  As  a  rough  guide,  however,  it 
may  be  said  tliat  refining  increases  the  value  from,  say,  £5  per  ton,  as  in  the  case  of 
rape  oil,  to  anything  up  to  £10,  as  in  the  case  of  cotton  seed  oil. 

A  perfectly  pure  oil  is  a  definite  chemical  body.  It  may  be  regarded  as  being 
formed  by  the  union  of  a  molecule  of  glycerine  with  a  molecule  of  fatty  acid  accom- 
panied by  the  withdrawal  of  a  molecule  of  water.  I  The  glycerine  is  definitely  constant 
from  oil  to  oil.  The  fatty  acid  varies  from  oil  to  oil,  and  by  its  variation  gives  the 
oil  its  characteristics.  All  piu'e  oils,  such  as  we  are  for  the  moment  considering,  are 
probably  identical,  in  so  far  as  they  are  colourless^ odourless-a^wLiaeteless.  Crude  oils 
differ  from  pure  oils  in  three  principal  respects.  In  the  first  place,  they  may  be  coloured. 
The  colouring  matter  is  derived  either  from  the  fleshy  portion  of  the  seed  from  which 
the  oil  is  recovered  or  from  the  husk  of  the  seed,  if  this  is  crushed  along  with  the  fleshy 
portion.  Secondly,  crude  oils  contam  vegetable  fibrous  matter  or  mucilage  or  other 
foreign  bodies  crushed  out  of  the  seeds  along  with  the  oil.  Such  mucilage  is  simply 
suspended  mechanically  in  the  oil.  Thirdly,  they  may  contain  free  fatty  acid  and 
free  glycerine,  caused  by  some  portion  of  the  oil  absorbing  water  and  spHtting  up. 
This  splitting-up  process,  or  hydrolysis,  as  it  is  called,  is  fi:equently  caused  by  careless 
or  crude  methods  of  manufacture,  as  in  the  case  of  palm  oil.  Even,  however,  with  the 
most  careful  manufacture,  some  fatty  acid  is  nearly  certain  to  be  present  in  the  crude 
oil,  the  rea.son  being,  apparently,  the  hydrolysis  of  the  oil  by  natural  proces.ses  in  the 
seed  itself  before  it  is  crushed — possibly  even  before  it  is  gathered.  The  presence  of 
free  glycerine  in  an  oil  is  rarely  objectionable,  for  it  is  colourless,  tasteless  and  odourless 
and  stable.  The  presence  of  free  fatty  acid  is  nearly  always  objectionable,  for  to  such 
may  usually  be  attributed  the  characteri.stic  taste  and  smell  of  an  oil,  while  in  addition, 
its  decomposition  turns  the  fat  or  oil  rancid.  The  possibility  of  such  acid  being 
present  is  the  prime  reason  why  vegetable  oils  are  not  in  favour  as  lubricants. 

In  addition  to  the  removal  of  mucilage,  of  colouring  matter,  and  of  free  fatty 
acid,  oil  refining  frequently  includes  a  fourth  class  of  operation.  On  a  cold  day  certain 
qualities  of  olive  oil  will  be  noticed  to  throw  do^^^l  a  flocculent  whitish  deposit.  Cotton 
seed  and  other  oils  likewise  become  cloudy  when  the  temperature  falls.  This  deposit 
is  "  stearine  " — or  "  margarine,"  as  it  is  frequently  and  somewhat  imfortmiately 
called — and  its  removal  is  desirable  in  certain  circumstances,  notably  so  if  the  oil  is 
to  be  used  for  bummg,  lubricating  or  edible  purposes.  The  "  stearine  "  itself  is  a 
valuable  substance  when  isolated,  and  is  made  use  of  in  the  manufacture  of  candles, 
margarine,  margarine  cheese  and  lard  substitute. 

The  processes  employed  in  oil  refining  are  either  mechanical  or  chemical,  or  a 


94         THE   PRODUCTION  AND   TREATMENT   OF   \^GETABLE   OILS 

combination  of  both.  Thus  mucilage  is  removed  mechanically.  Bleaching  is  in 
general  efifected  chemically,  but  is  frequently  accomplished  by  what  is  really  a 
mechanical  process.  Free  fatty  acids  are  removed  by  a  chemical  reaction.  "  De- 
margarination  "'  is  most  frequently  effected  by  physical  processes. 

Preliminary  Refining  in  the  Oil  Mill.  , 

A  certain  amount  of  preliminary  refining  is  commonly  conducted  on  the  oil  before 
it  leaves  the  oil  mill.  This  refinmg  aims  only  at  the  removal  of  the  mucilage,  etc.,  in 
the  oil.  Formerly,  it  was  conducted  simply  by  storing  the  oil  for  prolonged  periods, 
sometimes  extending  to  years,  in  storage  tanks,  wherein  the  foreign  matter  gradually 


Fig.  G1.— Filter  Press  for  (_)il — Mauluve,  AUiott. 

fell  to  the  bottom,  leaving  the  clear  oil  on  top.     Modern  practice  now  makes  use  of 
filter  presses,  and  so  very  greatly  economises  both  time  and  space. 

Filter  Presses. 
The  filter  press  is  used  in  many  industries  for  effecting  the  separation  of  solids 
from  liquids.  It  is  made  in  several  modifications,  but  always  follo^^•s  the  principle 
of  forcing  the  liquid  to  be  filtered  through  a  layer  of  cloth,  swansdown  or  twill.  A 
filter  press  suitable  for  use  in  an  oil  mill  is  illustrated  in  Fig.  61.  It  consists  primarily 
of  a  series  of  cast-iron  plates  formed  with  a  lug  at  each  side,  which  lugs  support  the 
plates  on  a  pair  of  steel  rods— usually  circular — extending  between  the  two  fixed  ends 
or  pedestals  of  the  press.  In  the  form  of  plate  shown  in  Fig.  62  an  edge  is  raised  up 
all  round  the  peripheiy  of  each  face,  so  that  when  two  plates  are  brought  together  the 
dished  centres  form  a  chamber  between  them.  Through  the  centre  of  each  plate  a 
circular  feed  hole  is  formed  for  the  oil.  The  method  of  working  will,  perhaps,  be 
understood  with  the  help  of  the  sketch.  Fig.  63.  For  each  plate  there  are  provided 
two  filtering  cloths  A,  B,  formed  with  central  holes  and  united  round  the  edges  of  these 
holes  by  means  of  a  short  cylinder  or  ring  of  cloth  C.     The  cloth  A  can  readily  be  rolled 


THE    REFINING    OF    OILS 


Fig.  62.— Filter  Press  Plate. 


up,  slipped  through  the  central  hole  in  the  plate  and  spread  out  flat  on  the  other  side. 

The  two  cloths  to  facilitate  the  assembly  of  the  plates  are  then  held  at  their  upper 

edges  by  means  of  clips  D  passing  on  to  a  rib  formed  across  the  top  of  th^  plate. 
When  all  the  plates,  thus  clothed, 

have  been  assembled  in  the  framework 

of  the  press,  the  pinion  E  (Fig.  61)  is 

rotated    by    means    of    a   tommy  -  bar 

inserted  in  holes  round  its  flange.    This 

pinion  engages  with  a  rack  extending 

from  the  sliding  head  F,  go  that  the 

action  results  in  the  press  plates   and 

their  cloths   being  closed   up  together. 

The  final  closure  of  the  plates  is  effected 

by  turning  down  the  half -covers  G  and 

screwing    up    the     hand -wheels    H   by 

means  of  levers.    The  chambers  between 

the  plates  are   thus  sealed  by  nipping 

the  cloths    between   the    raised    edges. 

Crude    oil    is    now   pumped    into    the 

press  at  the  right-hand  end,  and  flow- 
ing throxigh  the  central  feed  holes  fills 

all  the   chambers   between  the  plates. 

Under  the  pressure  of  the  oil  the  filter  cloths  are  pressed  backwards  until  they  meet 

the  support  of  the  plates.     The  faces  of  the  plates,  as  shown  in  Fig.  62,  are  formed 

with  vertical  grooves  connected  by  shoi-t  horizontal  grooves,  so  that  the  oil  filtering 

through  the  cloths  may  trickle  downwards  into  a 
gutter  formed  along  the  jilate  just  above  the  lower 
raised  edge.  From  this  it  is  conducted  through 
three  holes  into  a  central  passage  waj'^  J  (Fig.  63),  and 
so  through  cocks  K  (Fig.  61)  into  a  collecting  trough. 
Instead  of  joining  the  two  cloths  for  each  plate 
by  a  ring  of  cloth,  the  cloths  may  be  entirely 
separate.  The  central  holes  in  the  cloths  are  then 
nipped  to  the  edge  of  the  feed  hole  in  the  plate  by 
mean.s  of  a  clip  either  of  a  screw  or  bayonet- 
fastening  type.  Yet  another  alternative  metliod, 
one  finding  considerable  favour,  is  to  form  the 
raised  edges  of  the  plates  as  a  separate  frame  having 
lugs,  like  tlio.se  on  the  plates,  for  their  independent 
support  on  the  two  horizontal  bars.  This  design  of 
press  is  that  actually  shown  in  Fig.  61.  The  feed 
holes,  as  indicated  at  L  in  Fig.  63,  are  in  this  form 
placed  near  the  upper  edge  of  the  plates,  and  are 
continued  through  the  loo.se  frames  M.  A  hole  N 
conducts  the  oil  from  the  feed  passage  into  the 
chambers  between  the  plates.  Tlie  cloths  are  placed 
between  the  loose  frames  and  the  plates.  In  this 
way  the  edges  of  the  plates  and  the  feed  holes  are 

sealed  simultaneously  when  the  press  is  sci-ewed  up.     This  design  has  certain  advan- 
tages when  it  is  desired  to  remove  in  one  piece  the  cake  left  on  the  cloths. 


The   Ehgineeb" 
Fig.  63.— Two  Form 


Swain   Sc. 
of  Filter  Plates. 


96 


THE   PRODUCTION  AND  TREATMENT   OF  ^"EGETABLE   OILS 


The  method  adopted  for  closing  the  press  plates  also  raries  a  good  deal.  Thus 
it  may,  in  addition  to  the  manner  shown  in  Fig.  61,  be  effected  by  means  of  a  central 
screw  or  a  compressed  air  cylinder,  or  a  hydraulic  ram.  In  connection  with  the  feeding 
of  the  press  with  crude  oil  considerable  attention  has  to  be  devoted  to  the  fact  that 
the  filtration  towards  the  end  of  the  operation  becomes  slower,  so  that  a  lessened  feed 
is  required.  If  the  press  is  fed  by  means  of  a  belt -driven  pump,  a  rehef  valve  should 
be  provided  on  the  feed  i^ipe.  so  that  with  the  pump  rmining  uniformly  some  of  the 
feed  may  be  by -passed  when  the  speed  of  filtration  falls  off.     A  steam-driven  pump 


^_^                                         ^^^^^^^^^fiVVS.  r«                      ^^1 

^^.    y 

!  ' 

^•i.,..^  W 

y 

Fig.  ii4.— ■\Vashin;  Machine  for  Filter  Cloth> — Miiilove,  Alliutt. 


can  be  itself  regulated  to  suit  this  requirement,  and  therefore  does  not  require  the 
provision  of  a  relief  valve.  A  better  method  than  either  seems  to  be  the  adoption  of 
a  forcing  ram  worked  by  compressed  air.  The  flow  in  this  case  is  stated  to  be  entirely 
seK-ad  justing. 

As  usually  sujiplied  these  filter  presses  may  have  am-thing  from  six  to  forty-five 
chambers,  the  dimensions  of  the  plates  varying  from  13  in.  to  40  in.  square.  The  thick- 
ness of  the  cakes  left  in  them  is  from  1  in.  to  If  in.  Little  can  be  said  as  to  the  out;>r.t, 
for  this  varies  from  oil  to  oil,  and  with  the  one  oil,  according  to  its  previous  treatment, 
and  whether  or  not  it  is  filtered  hot  or  cold.  As  a  guide,  however,  it  may  be  said 
that  a  press  with  twenty -four  chambers  and  plates  25  in.  square — giving  a  total  filtering 
area  of  208  sq.  ft. — may  be  expected  to  filt-er  in  twenty-four  hours  140  cwt.  of  Unseed 
cocoa-nut,  or  fresh  olive  oil  :    100  cwt.  of  crude  cotton  oil  :    7'^  cwt..  of  crude  i-ape  or 


THE    REFINING    OF    OILS 


97 


stale  olive  oil  ;  or  16  cwt.  of  castor  oil.  The  length  of  time  for  which  the  press 
\vill  work  without  being  opened  for  cleaning  also  depends  upon  the  nature^of  the 
oil  being  filtered.  In  the  case  of  linseed  oil  the' press  may  be  run  continuously 
for  about  a  week.  It  would  then  be  allowed  to  stand  with  the  pressure  removed 
from  it  for,  say,  three  hoars,  at  the  end  of  which  time  it  would  be  opened  up 
and  the  cakes  formed  in  the  chambers 
removed.  Thereafter  it  is  ready  for  a 
further  run. 

Filter  Cloth  Washing  Machine. 

Occasionally,  and  particularly  when 
the  production  of  edible  oils  is  in  ques- 
tion, it  is  desirable  to  remove  the  press 
filter  cloths  and  wash  them.  A  washing- 
machine  for  tills  purpose  is  illustrated 
in  Fig.  64.  In  this  machine  the  cloths 
are  treated  in  a  hot  dilute  solution  of 
caustic  soda  which,  combining  with  the 
oil,  produces  soap  and  so  cleanses  the 
cloths  from  mucilage  and  dirt.  The 
machine  has  an  outer  casing  of  galva- 
nised steel  fixed  to  two  cast-iron  ends. 
The  internal  rotary  washing  compart- 
ment is  constructed  of  hard-rolled  brass 
plates  perforated  from  the  inside  in  a 
special  manner  so  as  to  avoid  the 
creation  of  burrs.  Five  lifters  or  rubbers 
are  provided  inside  the  drum,  while  in 
the  larger  sized  machines,  such  as  that 
illustrated,  there  is  a  central  partition. 
The  outer  casing  and  the  inner  drum 
are  both  provided  with  segmental  doors 
sliding  in  brass  guides.  Hand-turning 
gear  is  provided  for  bringing  the  two 
sets  of  doors  into  alignment  for  loading 
and  unloading  purposes.  The  shaft 
carrying  the  washing  compartment  jjasses  through  glands  in  the  cast  iron  ends  of 
the  casing,  and  is  supjjorted  externally  in  adjustable  roller  bearings.  It  is  driven 
through  a  silent  rocker  chain  from  a  shaft  at  the  back  of  the  machine.  This  shaft 
carries  two  loose  pulleys  for  crossed  and  oi)en  belts,  and  a  fixed  belt  pulley.  A  wonn 
and  a  worm  wheel  gear  is  pro\idcd  automatically  to  move  each  belt  alternately  on 
to  the  fixed  central  pulley,  so  that  tiie  direction  of  rotation  of  the  washing  compartment 
may,  during  a  run,  be  reversed  at  regular  intervals.  Steam  and  hot  and  cold-water 
valves  arc  arranged  on  the  casing  in  order  that  the  cloths  may  be  washed,  boiled,  and 
rinsed.  A  full  bore  waste  outlet  is  also  provided.  After  the  clotlis  have  been  removed 
from  the  machine  they  are  placed  in  a  centrifugal  hydro-e.xtractor,  which  removes 
the  bulk  of  the  water.  Thereafter  they  may  be  thoroughly  dried,  if  thought  necessary^ 
in  a  steam-heated  hot-air  rotary  drying  machine. 


Fk;.  ()0. — t't'iitrihisral  lOxtractoi-  lor  "  Foat^ 


••8 


THE   PRODITTION   AND   TREATMENT   OF   ^^:GETABLE   OILS 


The  Tkeatmext  of    "  Foots." 
In  all  oil  mills,  ■whether  the  presses  in  use  are  of  the  Anglo-American  or  the  cage 
type,  a  considerable  amotmt  of  meal  saturated  with  oil  escapes  from  the  press  and 


DriV.ne   Sfi3.  t 


Fig.  66.— Cotton-Seed  Oil  Eetinerv — Maiilove.  Alliott. 


accumulates  in  the  tanks  in  which  the  presses  stand,  the  oil  dishes,  and  so  on.  This 
material  is  knowii  as  "  foots,"  and  to  avoid  waste  is  treated  so  as  to  separate  the  bulk 
of  the  oil  from  it.  A  common  method  of  effecting  this  separation  is  by  the  employment 
of  a  ■■  centrifugal  ""  such  as  is  shown  in  Fig.  65.     This  machine  consists  of  a  cast-iron 


THE   REFINING   OF    OILS  99 

casing  enclosing  a  basket  of  tinned-steel  wire  with  a  pressed-steel  top  ring  and  bottom. 
The  basket  is  mounted  on  a  vertical  shaft  supported  at  the  top  and  bottom  on  ball 
bearings,  and  driven  through  friction  cones  from  a  horizontal  cross-shaft.  The  peri- 
pheral speed  of  the  basket  is  usually  about  9,000  ft.  per  minute.  The  slurry  is  placed 
within  it,  and  in  a  very  short  time  the  bulk  of  the  oil  is  driven  off  out  of  the  basket. 
This  oil  may  be  mixed  with  that  extracted  in  the  usual  way  or  sold  separately.  The 
residue  in  the  basket  is  foimd  to  contain  about  the  same  percentage  of  oil  as  does  the 
original  seed  before  pressing.  It  is  therefore  returned  to  the  meal  kettle  and  worked 
back  to  the  press  with  the  fresh  meal. 

Li  addition  to  the  preliminary  separation  of  mechanical  impurities  carried  out 
as  mentioned  above,  the  refining  of  oil  comprises  the  removal  of  free  fatty  acids  and 
of  bleaching  to  get  rid  of  the  colouring  matter.  Broadly,  it  may  be  said  that  the 
removal  of  the  free  fatty  acids  is  necessary  if  the  oil  is  to  be  used  for  edible  purposes, 
and  that  bleaching  is- desirable  if  it  is  to  be  used  for  the  manufacture  of  paints  or 
varnishes. 

Removal  of  Free  Fatty  Acids. 

By  removing  the  free  fatty  acids  from  the  crude  oil,  the  oil  is  deprived  of  the 
elements  which  give  it  its  characteristic  odour  and  taste,  and  which  render  it  liable 
to  decomposition.  At  the  same  time  its  colour  will  probably  be  improved,  for  the 
free  fatty  acids  are  a  cause  of  discoloration  in  addition  to  the  colouring  matter  absorbed 
by  the  oil,  during  its  extraction,  from  the  husks  of  the  seeds. 

The  standard  method  of  removing  the  fatty  acids  is  to  treat  the  crude  oil  with 
caustic  soda  solution,  carefully  regulated  in  strength  and  amount,  and  at  a  carefully 
regulated  temperature.  The  soda  solution  combines  with  the  free  acids  to  form  a 
soap,  but  is  not  sufficient  in  amount  to  go  farther  and  saponify  any  material  amoimt 
of  the  neutral  oil.  It  is  here  to  be  noted  that  more  caustic  soda  has  to  be  added  to 
the  oil  than  is  theoretically  necessary  to  neutralise  the  percentage  of  free  acid  revealed 
by  analysis  in  the  crude  oil.  The  surplus  soda  does  not,  however,  attack  the  neutral 
oil  miless  of  course  it  is  permitted  to  be  present  in  an  altogether  excessive  amount. 
The  reason,  both  for  the  procedure  and  of  the  result,  lies  in  the  fact  that  the  action 
between  a  given  amoujit  of  caustic  soda  and  a  given  amomit  of  oil  will  cease  at  a  point, 
short  of  completion,  at  which  a  state  of  equilibrium  is  established  between  the  amount 
of  soap  formed  and  the  amount  of  oil  and  of  caustic  soda  .still  left  micombined.  The 
point  in  question  is  influenced  by  the  temperature  at  which  the  reaction  is  conducted. 

On  the  neutraUsation  of  the  free  fatty  acids  being  completed,  there  is  thus  left 
in  the  refining  kettle  a  mixture  consisting  of  soap,  acid-free  oil  and  caustic  soda  in 
solution.  This  mixture  is  allowed  to  stand  for  some  hours  to  permit  the  soap,  soda 
solution  and  any  mucilage  or  albuminous  matter  to  sink  to  the  bottom,  while  the  oil 
rises  as  a  clear  hquid  to  the  top.  The  clear  oil  is  then  dra\^Ti  off  for  further  treatment. 
The  residue  at  the  foot  of  the  kettle,  containing  as  it  does,  a  certain  amount  of  neutral 
oil  besides  the  soda,  etc.,  is  removed  separately,  and  is  sold  to  the  soap  maker  as 
"soap  stock."  To  facihtate  the  settling  out  of  the  soap,  etc.,  from  the  oil,  salt  is 
sometimes  thrown  into  the  kettle,  for  soda  soap  is  insoluble  in  salt  water. 

The  clear  oil  has  next  to  be  wa.shed  with  water  to  remove  all  traces  from  it  of 
the  soda.  Thereafter  it  is  treated  in  a  vacuum  still  to  drive  off  any  volatile  fatty 
acids  which  may  linger  in  it,  as  well  as  the  last  traces  of  moisture  left  in  it  by  the 
washing  process.  A  vacuum  still  is  used  in  order  that  the  volatile  acids  and  the 
moisture  may  be  driven  off  at  a  temperature  below  that  which  will  deleterioiisly  affect 
the  oil. 


100      THE   PRODUCTION   AXD   TREATMENT   C»F   ^^:GETABLE   OILS 

Bleachtsg. 

The  oil  may  or  may  not  now  have  to  be  bleached.  If  it  is  to  be  used  for  edible 
purposes,  it  is  desirable  that  it  should  be  bleachetl  by  means  of  fullers  earth  or  such- 
hke  absorbent  material.  For  other  purposes  chemicals  liberating  chlorine  or  oxygen 
may  be  used. 

Treatment  with  fuller's  earth,  animal  charcoal,  etc..  not  only  helps  to  bleach 
the  oil  :    it  also  assists  in  deodorising  it.     The  process  consists  in  thoroughly  stirring 


( 

1 

r^ 

( 

3kj 

j 

r 

I 

i 

ir 

J 

np 

Fig.  67. — Vacmim  Pan  and  Condenser. 


the  dry  absorbent  powder  into  the  oil  when  gently  heated  and,  after  agitation  for  a 
short  time,  in  passing  the  liquid  through  a  filter  press  such  as  we  have  described  above. 
The  earth  or  charcoal  with  the  absorbed  colouring  matter  is  retained  on  the  filter 
cloths,  while  the  clear  oil  is  drawn  off.  The  filter  press  is  usually  arranged  to  permit 
steam  to  be  blown  through  it  after  filtering  is  completed.  In  this  way  the  cakes  are 
washed  free  from  oil,  so  that  on  the  press  being  openetl  the  earth  falls  out  as  a  powder. 
It  may  surprise  some  to  learn  that  oils  can  be  bleached  in  the  above  purely 
mechanical  manner.     The  explanation  of  the  matter  lies  in  the  fact  that  the  colouring 


THE    REFINING    OF    OILS  lOl 

substance  in  the  original  seed  is.  in  general,  in  the  form  of  a  powder,  and  passes  as 
such  into  the  oil. .  It  can  therefore  be  absorbed  and  held  back  by  the  earth  or  charcoal. 
It  will  be  noticed  that  this  method  bleaches  the  oil  by  the  direct  removal  of  the  colouring 
matter.  A  similar  end  is  achieved  by  the  sulphuric  acid  method,  which  is  applied 
occasionally  for  bleaching  certain  oils.  The  acid  dehydrates  or  chars  the  colouring 
matter  and  other  impurities,  and  causes  them  to  coagulate,  so  that  they  may  readily 
be  removed  by  tilti'ation  or  sedimentation.  This  treatment  incidentally  secures  the 
removal  of  any  moistui-e  in  the  oil,  by  reason  of  the  strong  attraction  for  water  posse.ssed 
by  sulphuric  acid.  As,  however,  some  acid  may  remain  behind  in  the  bleached  oil,  the 
method  is  not  usually  adopted  if  the  oil  is  to  be  used  for  edible  or  lubricating  purposes. 

Bleaching  by  means  of  chlorine  or  oxygen  does  not  secure  the  removal  of  the 
colouring  matter.  The  colouration  is  destroyed  by  the  oxidation  of  the  colouring 
matter,  but  this,  when  oxidised,  is  allowed  to  remain  behind  in  the  oil.  The  chemicals 
used  are,  in  general,  such  as  to  render  the  process  unsuitable  for  application  to  the 
treatment  of  an  edible  oil.  In  most  cases  the  oxygen  or  chlorine  is  generated  by 
chemical  reaction  within  the  oil  itself.  Thus  bleaching  by  means  of  oxygen  may  be 
effected  by  adding  to  the  oil  manganese  dioxide  and  sulphuric  acid.  Similarly,  chlorine 
may  be  generated  by  adding  bleaching  powder  and  hydrochloric  acid.  In  one  case 
manganese  sulphate,  and  in  the  other  calcium  chloi-ide,  is  left  behind  in  the  oil,  and 
has  subsequently  to  be  removed  by  washing.  Further,  in  both  cases  the  reaction  of 
the  chemicals  results  in  the  formation  of  water. 

Many  other  methods  of  bleaching  oils  by  means  of  chemicals,  or  otherwise,  are 
practised  or  have  been  proposed.  It  is  not  necessary  for  us  here  to  discuss  these, 
for  they  belong  more  to  the  chemical  than  to  the  engineering  side  of  our  subject. 
We  need  only  remark  that  one  of  the  oldest  and  one  of  the  very  best  methods  is  by 
exposing  the  oil  to  the  action  of  sunlight  and  air.  This  process  results  in  the  natural 
oxidation  of  the  colouring  matter,  and  is  extensively  adopted  in  the  case  of  linseed, 
poppy  and  walnut  oils,  as  used  by  artists.  It  is.  of  course,  a  very  slow  method. 
Recently,  the  bleaching  of  oils  by  means  of  ultra-violet  rays  has  attracted  some 
attention. 

Cotton  Oil  Refining. 

The  arrangement  of  a  typical  refinery  for  treating  cotton-seed  oil  is  reproduced 
in  Fig.  66.  The  oil  in  this  case  is  fir.st  heated  by  steam  in  a  mixing  tank  A  until 
it  reaches  a  temperature  of  about  140°  F.  Thereafter  the  oil  is  violently  agitated 
by  means  of  compressed  air.  the  temperature,  meanwhile,  being  kept  as  near  140°  F. 
as  possible.  During  the  agitation  cau.stic  soda  solution  from  the  tanks  C,  D,  is  run 
into  the  mixing  tank.  As  this  solution,  being  heavier  than  the  oil.  tends  to  sink  to 
the  foot,  care  is  necessary  if  it  is  to  be  brought  properly  into  intimate  contact  with  the 
oil.  This  is  secured  by  distributing  the  solution  evenly  over  the  surface  of  the  oil, 
and  by  the  vigorous  agitation  to  which  the  contents  of  the  mixing  tank  are  subjected. 
When  it  has  been  ascertained  by  testing  samples  that  sufficient  caustic  soda  has  beg 
added  to  neutralise  the  acid  reaction  of  the  oil,  the  charge  is  allowed  to  standand 
settle  in  the  mixing  tanly  The  settling  is  usually  sufficiently  complete  at  the  end  of 
about  twelve  hours  to  permit  the  clear  supernatant  oil  to  be  drawn  off  and  passed 
into  the  washing  tank  H.  Li  so  doing,  gi'eat  care  ha.s  to  be  exercised  that  none  of 
the  residue  is  passed  off  with  the  clear  oil.  This  residue  is  ultimately  drained  into 
the  mucilage  tank  G. 

In  the  washing  tank  the  oil  is  gently  heated  and  washed  with  water  to  remove 
the  caustic  soda  solution  remaining  in  it.     The  water  is  distributed  uniformly  over 


10-2 


THE   PRODUCTION   AND   TREATMENT   OF   \EGETABLE   OILS 


the  surface  of  the  oil,  which,  as  before,  is  violently  agitated  by  means  of  compressed 
air  jets.  On  aUowing  the  charge  to  settle,  the  oil  rises  to  the  top.  The  water  con- 
taining the  soda  in  solution  sinks  to  the  foot  of  the  tank  and  is  drawn  off.  For  the 
production  of  the  best  edible  oils  two  or  three  washings  may  be  required. 


Fig.  6S. — Cocoa-nut  C»il  Ketinerr— Man.ove.  .Uliott. 

If  the  oU  is  for  edible  purposes — say  for  the  manufacture  of  margarine  or  lard 
substitute — it  will  either  be  passed  without  being  bleached  into  the  vacuum  pan  N 
or  will  be  bleached  by  the  fuller  s-earth  method  already  referred  to.  Oils  for  other 
than  edible  purposes  are  passed  from  the  washing  tank  into  the  bleaching  tank  B. 


THE    REFINING    OF    OILS  103 

Here  they  are  agitated  in  the  usual  way  and  are  subjected  to  the  joint  action  of  hydro- 
chloric acid  delivered  from  the  cast-iron  tank  E,  and  of  bleaching  powder  solution 
dra\m  from  the  slate  tank  F.  When  bleaching  is  completed,  the  charge  is  returned 
to  the  tank  H,  wherein  the  bleaching  chemicals  and  the  salts  formed  by  them  are 
washed  out  of  it.  The  procedure  may  be  slightly  varied  by  passing  the  oil  direct 
from  the  tank  A  into  the  bleaching  tank.  This  avoids  the  fii'st  washing,  but  I'esults 
in  a  certain  amount  of  acid  being  wasted  in  the  neutralisation  of  the  caustic  soda 
solution  remaining  in  the  oil.  This  neutralisation,  it  may,  however,  be  noted,  results 
in  the  production  of  sodium  chloride,  the  presence  of  which  in  the  oil  is  by  no  means 
harmful,  but  frequently  of  assistance. 

The  oil  dra\ra  from  tlie  washing-tank  is  now  passed  into  the  vacuum  pan  N — 
showTi  separately  in  Fig.  67.  Here  it  is  mechanically  agitated  and  heated  under  a 
vacuum,  so  as  to  drive  off  the  moisture  and  any  free  volatile  fatty  acids  which  maj' 
yet  remain  in  it.  The  expelled  products  are  caught  in  the  condenser  P.  If  the  oil 
is  an  edible  oil,  and  if  it  is  required  in  a  bleached  condition,  some  refiners  combine 
the  fuller's-earth  treatment  with  the  treatment  of  the  oil  in  the  vacuum  pan.  On 
leaving  the  pan,  the  oil  is.  in  such  a  case,  passed  through  a  filter  press,  whereafter  it 
is  ready  for  the  market. 

Cocoa-nut  Oil  Refinixg. 

A  small  refinery  for  cocoa-nut,  palm  kernel  and  similar  oils  is  illustrated  in  Fig.  68. 
The  procedure  in  this  case  is,  in  prmciple,  similar  to  that  followed  in  the  cotton  oil 
refinery  described  above,  except  that  no  provision  is  made  for  bleaching  the  oils 
chemically  since  they  are  here  intended  solely  for  edible  purposes. 

The  oil.  as  received,  is  first  passed  through  a  filter  press  A  to  remove  mucilage, 
etc.,  and  is  thence  run  into  a  storage  tank  B.  From  this  it  is  passed  by  gravity  into 
the  refining  tank  C  situated  on  the  floor  below,  where  it  is  heated,  agitated,  and  treated 
with  caustic  soda  solution  from  the  tanks  D  in  the  usual  way.  After  settling,  the 
mucilage  and  other  residue  is  dra^vii  off  into  the  pitch-pine  tank  E  situated  on  the 
ground  floor,  while  the  clear  oil  is  passed  into  the  tank  F  on  the  first  floor.  In  this 
tank  F  the  oil  is  washed  with  hot  water  from  the  tank  G  and  is,  in  addition,  heated 
by  means  of  a  steam  coil.  The  tank  F.  in  fact,  not  only  .serves  for  washing  the  oil, 
but  also  acts  as  a  prehminary  still  for  driving  off  a  certain  amount  of  the  volatile 
free  fatty  acids  which  yet  may  linger  in  the  charge.  By  means  of  a  rotary  pump  H. 
the  charge  in  the  tank  F  can  be  sent  back  to  the  refining  tank  C.  so  as  to  be  returned 
to  the  tank  F  for  further  washing  and  heating.  The  oil,  previously  treated  with 
fuller's  earth  or  not.  as  is  thought  desirable,  is  passed  from  the  preliminary  still  F 
through  a  second  filter  press  J.  and  thence  into  a  finishing  still  or  vacuum  pan  K  of 
the  design  illustrated  already  in  Fig.  67. 

Demargarin.vtiox. 
Certain  oils,  notably  cotton-seed  and  olive,  as  we  have  already  remarked,  throw 
downi  a  deposit  of  "  stearine  "  when  the  temperature  falls  below  a  certain  point. 
Chemically,  an  oil  is  formed  bj-  the  union  of  a  fatty  acid  with  glycerine  accompanied 
by  the  withdrawal  of  a  certain  number  of  atoms  which,  taken  together,  constitute 
water.  The  body  fonned  by  such  a  union  is  knovm  as  a  glyceride.  A  glyccride  is 
thus  an  oil,  but  no  actual  oil,  so  far  as  we  know,  is  formed  of  one  and  only  one  glyceride. 
Stearine  is  a  glyceride,  being  formed  by  the  union  of  stearic  acid  with  glycerine. 
Palmitine — palmitic   acid   and   glycerine — is  another.     And   there  are  many   more, 


104       THE   PRODUCTION   AND  TREATMENT   OF  VEGETABLE   OILS 

such  as  oleine.  linoline,  linolenme,  and  so  on.  These  gh'cerides  solidify  at  different 
temperatures.  Thus,  of  those  mentioned,  stearine  and  pahuitine  may  be  said  to  have 
relatively  high  solidifying  points,  and  oleine,  linoline  and  linolenine,  relatively  low 
soUdifying  points.  Taking  the  particular  case  of  cotton-seed  oil,  we  find  that  this  oil 
consists  prmcipally  of  a  mixture  of  palmitine,  oleine  and  linoline.  When  the  tempera- 
ture falls,  the  palmitine  solidifies  out,  while  the  oleine  and  linohne  are  still  liquid. 
The  "  stearine  "  deposited  by  cotton-seed  oil  is,  therefore,  not  stearine,  but  palmitine. 
From  other  oils — for  example,  from  olive  oil — it  may  consist  of  a  mixture  of  true 
stearine.  palmitine.  and  other  glycerides  solidifying  at  a  relatively  high  temperature. 


^^ T^^^^H^^^^^^^^^^^^fek^^^^^^^^SiK^^^^HRSB 


F:o.  69. — Stearine  Presses  for  Demargarinating  Oil. 

The  extraction  of  the  "  stearine  "  is  an  important  operation.  ])articularly  in  the 
case  of  cotton-seed  oil.  This  oil.  after  being  "  demargarinated,"  is  knowii  as  "  winter 
cijl,"  because  it  •will  not  throw  dov,ii  a  deposit  or  become  cloudy  at  temperatures 

/  normally  occurring  in  winter.  A  usual  method  of  carrjing  out  the  demargarmation 
is  to  cool  the  oil  artificially  luitil  the  "  stearine  "  portions  solidify,  and  then  to  pass 

I the  whole  through  a  filter  press.     A  slightly  different  method  consists  of  completing 

the  freezing  of  the  whole  oil  in  flat  pans,  wrapping  the  frozen  cakes  in  bagging  and 
pressing  them  in  a  hydraulic  press.  Under  the  pressure,  the  portions  of  the  oil  havuig 
the  lowest  freezing-point.  Hquefy.  and  are  forced  out  and  drain  away.  A  set  of  stearine 
presses,  suitable  for  this  method  of  working,  is  illustrated  in  Fig.  69.  The  presses  differ 
considerably  from  those  of  the  Anglo-Amei-ican  type  used  for  crushing  seeds.  Each 
is  provided  with  a  ram  12  in.  in  diameter  and  suitable  for  a  working  pressure  of  2  tons. 
Asquare  table  is  formed  at  the  head  of  the  ram.  and  on  to  this  a  four-wheeled  carriage 
can  be  rim  on  I'ails  from  either  side  of  the  press.     The  carriage  is  provided  with  catches, 


THE    REFINING    OF    OILS  105 

which  can  be  hhiged  down  to  engage  the  columns  of  the  press,  and  with  two  vertical 
guide  bars,  which,  when  the  ram  rises,  enter  holes  in  the  press  head  and  so  hold  the 
carriage  steady.  The  expressed  oil  is  caught  in  the  box-like  carriages.  There  are 
two  carriages  for  each  press,  so  that  one  may  be  filled  while  the  other  is  under  pressure. 
Special  provision  is  made  to  ensure  that  the  pressure  shall  be  applied  very  slowly. 
The  refrigerated  cakes  are  pressed  between  steel  plates.  These  are  sufficiently  large 
to  accommodate  four  cakes  each. 

All  the  machines  and  plant  illustrated  in  this  chapter  represent  the  practice  of 
Manlove,  Alliott  &  Co.,  Ltd.,  Nottingham. 


CHAPTER    XIII 
THE   HYDROGENATION   OR   HARDENING   OF   OILS 

Fatty  vegetable  and  animals  oils  may  be  described  as  consisting  of  a  glycerine 
part  and  an  acid  part.  The  composition  of  the  glycerine  part  is  constant.  The 
compo.sition  of  the  acid  part  vaj-ies  from  oil  to  oil.  and  is  characteristic  of  any  one  oil, 
or  of  any  one  gi-oup  of  oils. 

Several  important  vegetable  and  animal  oils  contain  an  acid  part  having  the 
general  chemical  formula  C„H2„0.^.  Among  these  we  have  butter  fat,  cocoa-nut 
oil,  palm  oil,  palm  kernel  oil,  lard,  tallow,  and  various  '"  butters."  such  as  cocoa, 
mace  and  nutmeg  butters.  It  will  be  noticed  that  the  oils  and  fats  mentioned  are 
in  general  characterised  by  the  possession  of  a  thick  consistency  ;  that  is  to  say,  they 
have  high  melting-points,  or,  in  other  words,  they  are  naturally  "'  hard."' 

Man}'  other  important  vegetable  and  animal  oils  differ  from  those  just  mentioned 
in  that  their  acid  parts  fail  to  tit  the  general  formula  quoted  to  the  extent  of  two,  four, 
six  or  eight  atoms  of  hydrogen.  Thus,  in  rape  oil.  and  certain  fish  oils,  two  hydrogen 
atoms  are  missing.  Four  are  absent  in  the  acid  parts  of  soj-a  bean  oil  and  cotton-seed 
oil.  In  linseed  oil  six  atoms  are  missing,  and  in  certain  liver  and  blubber  oils  eight 
atoms  are  awanting.  All  these  oils,  it  will  be  noticed,  are  in  general  characterised  by 
the  possession  of  a  liquid  consistency.  In  passing  it  should  be  observed  that  castor 
oil  does  not  appear  under  either  division.  This  oil  is  exceptional,  for  its  acid  part 
contains  not  two,  but  three  atoms  of  oxygen. 

The  oils  of  the  second  division — or.  to  be  quite  exact,  the  acid  parts  of  these  oils — 
are  termed  unsaturated,  for  they  are,  theoretically  at  least,  capable  of  taking  up  and 
combining  with  additional  atoms  of  hydrogen.  In  practice,  however,  under  normal 
conditions,  hydrogen,  even  in  the  na.scent  state,  is  quite  without  action  on  fatty  oils. 
The  great  commercial  value  attaching  to  the  power  of  being  able  to  convert  an 
unsaturated  into  a  .saturated  oil  has  led  to  mucii  investigation  of  the  matter.  It  has 
been  discovered  that  the  addition  of  the  hydrogen  atoms  can  be  effected  if  the  oil  is 
suitably  treated  with  hydrogen  gas  in  the  presence  of  finely  divided  nickel  or  palladium. 
Each  of  these  metals  acts  as  a  catalyst,  and  is  left  unaltered  after  the  hydrogen  has 
been  taken  up  by  the  oil. 

These  are  the  broad  chemical  aspects  of  the  process  we  are  now  discussing. 
Wherein  lies  its  commercial  applicability  I  The  answer  to  this  question  can  be  given 
in  a  general  statement.  For  the  purposes  of  modern  industry  the  world's  sujjply  of 
natural  fats  is  deficient,  while  the  supply  of  liquid  oils  is  superabundant.  The  liydro- 
genation  process  permits  us  to  make  good  the  deficiency  by  converting  some  of  the 
superabundant  liquid  oils  into  hard  fats. 

As  an  instance  of  the  commercial  applicability  of  the  hydrogenation  jn'ocess.  we 
may  look  for  a  moment  at  the  .soap-making  industry.  The  ideal  substance  for  tlie 
.soap  maker  to  work  with  may  be  said  to  be  tallow.  It  is  a  firm  substance,  and  yields 
a  firm  soap  such  as  we  are  accustomed  to.  Tallow,  howevei-.  is  expensive,  and  is 
obtainable  only  in  strictly  limited  amounts.  The  soap  maker  accordingly  falls  back 
upon  some  of  the  harder  oils,  .such  as  cocoa-nut  oil,  palm  oil.  and  palm-kernel  oil. 


THE    HYDRC^GEXATION    OR   HARDENING   OF    OILS  107 

These  oils  are  also  expensive  and  are  in  increasing  demand  in  other  industries.  If, 
however,  the  soap  maker  tries  to  replace  them  with  one  or  other  of  the  abundant 
naturally  liquid  oils,  such  as  whale  oil,  soya-bean  oil,  and  so  on.  his  product  loses 
greatly  in  quality,  and  is  apt  to  be  a  soft,  sticky  mass,  mausable  or  unsaleable  as  soap 
for  many  purposes.  By  hardening  these  oils  before  using  them  in  the  soap  kettle, 
he  obtains  a  substance  practically  identical  with  tallow  without  affecting  the  yield 
from  them  of  that  valuable  by-product  of  the  soap-making  industry,  glycerine.  The 
hydrogenation  process  thus  throws  open  to  the  soap  maker  a  wide  range  of  oils  which 
otherwise  would  be  next  to  useless  for  his  purpose. 

Similar  remarks  applj'  to  the  candle-makmg  industry,  which,  again,  calls  largely 
for  fats  rather  than  oils.  For  certain  edible  productions,  notably  margarine  and 
chocolate,  fats  are  now  in  demand  to  a  greater  extent  than  can  be  conveniently  met 
from  natural  sources  of  supply.  Whatever  may  be  the  case  to-day — it  is  verj'  difficult 
to  find  out  exactly  how  matters  do  stand  at  present — it  is  certain  that  artificialh- 
hardened  oils  ^\'ill  soon  be  in  extensive  and  acknowledged  use  for  edible  purposes. 
Just  for  the  moment  there  is  a  feeling  of  vmcertainty  as  to  this  employment  of  them, 
for  it  is  not  yet  settled  how  far  the  possible  presence  in  the  hardened  oils  of  a  small 
amomat  of  the  nickel  or  other  catalyst  is  harmful  to  the  human  constitution. 

The  chief  oil  hardened  at  present  is  whale  oil.  Increasing  quantities  of  cotton- 
seed, linseed,  soya-bean,  cocoa-nut,  and  other  oils  are.  however,  also  being  subjected 
to  the  process,  so  that  the  subject  is  one  quite  properly  faUing  within  the  scope  of 
this  volume.  With  regard  to  the  hardening  of  cocoa-nut  oil,  a  word  of  explanation  is 
no  doubt  desirable.  This  oil  is  just  on  the  border  line  between  the  true  oils  and  the 
true  fats.  It  is  one  thing  in  one  part  of  the  world,  and  the  other  in  another  part.  All 
its  acid  part  is  not  saturated,  but  contains  portions  of  imsaturated  acids.  It  is  therefore 
capable  of  absorbing  a  certain  amomit  of  hydrogen,  and  so  becoming  harder  than  it  is 
normally  in  this  climate. 

Hardened  oils  are  white,  tasteless,  odourless,  substances  of  tallow-like  consistency. 
Theoretically  at  least,  they  should  all  be  identical,  whatever  may  be  the  particular  oil 
started  %rith,  and  in  practice  such  identity  seems  to  be  attained,  at  least  in  the  oil 
as  freshly  hardened,  but  there  is  some  uncertainty  whether  a  hardened  oil  if  kept  long 
enough  will  or  will  not  develop  some  characteristics  of  its  parent.  Thus,  hardened 
whale  oil  may,  sooner  or  later,  develop  a  fi.shy  smell,  and  hardened  cocoa-nut  oil  the 
characteristic  smell  of  cocoa-nuts.  In  practice,  however,  the  oils  are  usually  hardened 
at  the  soap  works,  or  wherever  else  they  are  to  be  used,  or  are  otherwise  employed 
with  but  little  interval  between  being  hardened  and  being  treated  in  industrial  processes. 
The  point  is  of  importance,  for  there  are  distinct  signs  that,  in  the  near  future,  certain 
oils  will  be  hardened  before  shipment  to  this  countr}^  Thus  the  process  is  attracting 
considerable  attention  from  the  soya-bean  oil  producers  in  Japan  and  Jlanchuria, 
the  idea  being  that  hardened  oils  may  be  sliipped  and  carried  without  ri.sking  that 
loss  through  leakage,  etc.,  which  is  a  serious  item  in  the  shipment  of  liquid  oils. 

The  Technology  of  Oil  Hardening. 

Coming  to  the  technology  of  the  process  we  find  that  success  is  dependent  primarily 
upon  two  circumstances,  first,  the  careful  preparation  of  the  catalyst,  and,  secondly, 
the  use  of  very  pure  hydrogen.  Veiy  little  variation  of  procedure  may  quite  readily 
result  in  an  entire  failure  to  harden  the  oil. 

The  catah'st  commonly  used  on  a  commercial  scale  is  metallic  nickel  prepared 
in  a  finely-divided    .state  by  chemical  precipitation.     Once  made  it   must  be  kept 


Ids      THE  PRODUCTIOX   AND  TREATNEEXT   OF   ^'EGETABLE   OILS 

rigorously  apart  from  certain  other  substance*,  notably  air.  moisture,  sulphur, 
arsenic,  carbon  monoxide,  methane,  etc.  These  substances  oxidise  or  otherwise  react 
on  the  metaUic  nickel,  and  quite  destroy  its  catalytic  action.  Thus  it  is  stated  that 
a  tenth  of  1  per  cent,  of  sulphuretted  hydrogen,  if  present  in  the  hydrogen  used  in 
the  process,  will  prevent  the  hydrogenation  of  the  oil. 

The  effect  of  these  substances  on  the  catalyst  is  felt  in  three  directions.  First, 
a*  \re  have  said,  it  means  that  the  hydrogen  used  must  be  very  pure,  and  free  especially 
from  moistm^  and  sulphur  compounds.  Secondly,  the  oil  to  be  hardened  must  be 
thoroughly  freed  as  a  prelimLuary  from  the  moisture  which,  when  received,  it  is  certain 
always  to  contain.  Thirdly,  in  preparing  the  catalyst  a  stage  is  reached  when  it 
must  be  treated  and  handled  out  of  contact  with  the  atmosphere. 

Given  the  satisfactory-  attainment  of  these  conditions  the  process  is  simple.  The 
oil  with  the  catalyst  added  is  heated  m  an  atmosphere  of  hydrogen  inside  a  closed 
vessel — an  autoclave — fitted  with  a  mechanical  agitator.  The  oil  and  hydrogen  are 
brought  into  ultimate  contact  and  at  the  end  of  three  to  four  hours  the  absorption  is 
found  to  be  complete.  The  temperature  at  which  the  work  is  carried  on  is  of  great 
importance.  It  appears  that  for  any  given  pressure  of  hydrogen  inside  the  autoclave 
there  is  a  definite  temperatiu^e  which  must  be  reached  before  the  absorption  begins. 
At  atmospheric  pressure  this  temperature  appears  to  be  about  250'  C.  In  practice 
such  a  temperature  would  almost  certainly  result  in  the  hardened  oil  being  discoloured. 
To  avoid  this  some  temperature  approximating  2(H.>'  must  be  used.  The  pressure 
of  the  hydrogen  has  to  be  increased  above  atmospheric  as  the  temperature  is  decreased. 
A  normal  working  condition  is  a  temperature  of  ITO"^  to  ISO'  C.  in  conjunction 
with  a  pressure  of  70  to  80  lb.  per  square  inch. 

When  the  absorption  is  complete  the  oil  is  nm  out  <rf  the  autoclave,  cooled,  filtered, 
and  allowed  to  solidify. 

For  the  purpose  of  thL<  and  the  succeeding  chapter  we  have  made  a  close  study 
of  the  hydrogenation  and  hydrogen -producing  plants  designed  and  patented  by 
Mr.  Howard  Lane,  of  the  Laboratory.  Ashford.  Middlesex.  Mr.  Lane  has  kindly 
allowed  us  to  inspect  when  at  work  the  experimental  plants  which  he  has  erected  at 
his  laboratory.  To  avoid  creating  a  misapprehension  we  desire  to  make  it  quite  clear 
at  this  point  that  we  are  not  dealing  with  a  system  or  plant  which  is  only  in  the  experi- 
mental stage.  The  generation  of  pure  hydrogen  is  a  subject  which  has  engaged 
Mr.  Lanes  attention  since  1903.  The  development  of  his  oil-hardening  plant  followed 
upon  the  commercial  success  of  his  ideas  as  to  the  generation  of  hydrogen.  Many 
installations,  both  of  the  hydrogen  plant  and  the  hydrogenarion  plant  erected  to  his 
designs,  are  to-day  successfully  at  work  on  a  large  scale  both  in  this  country  and 
abroad.  It  is  proposed  in  this  chapter  to  describe  a  t>-pical  hydrogenation  plant 
on  the  Lane  system,  and  in  the  next^ — because  of  the  vital  importance  to  the  success 
of  the  hardening  process  of  an  inexp«isive  supply  of  pure  hydrogen — to  describe  the 
Lane  system  of  generating  hydrogen. 

In  the  engraving  (Fig.  70),  we  reproduce  the  general  plan  of  an  oil-hydrogenising 
plant  erected  to  Mr.  Lanes  designs.  As  set  to  work  in  the  first  instance,  this  factory- 
has  a  capacity  for  treating  I  ton  of  oil  per  hour,  but  throughout  provision  is  made 
for  trebling  the  plant  and  the  output.  In  this  chapter  we  are  concerned  solely  with 
the  lower  portion  of  the  plan — ^the  oil  treatment  department.  The  upper  portion — 
more  than  50  per  cent,  of  the  whole — represents  the  lay-out  of  the  hydrogen-producing 
plant  which  we  will  deal  with  in  otir  next  chapter. 


INSERT  FOLDOUT  HERE 


THE    HYDROGENATION    OR    HARDENING    OF    OILS  109 

Reception  and  Desiccation  of  the  Raw  Oil. 

The  raw  oil  is  received  at  the  works  at  the  point  marked  A  in  the  lower  left-hand 
corner  of  the  plan.  The  fir.st  operation  is  to  remove  the  oil  in  a  cleanly  and  thorough 
manner  from  the  barrels  and  to  pass  it  into  steel  storage  tanks.  As  the  raw  oil  may 
be  naturally  thick — such  as  is  the  case  if  cocoa-nut,  palm,  or  palm-kernel  oil  is  being 
treated — means  have  to  be  provided  for  heating  it  so  that  the  barrels  may  be  properly 
emptied  and  the  oil  in  the  storage  tanks  may  be  kept  sufficiently  liquid  to  be  pumped 
on  to  the  next  stage.  The  means  provided  consist  of  steam  jets  for  heating  the  barrels 
and  flat  steam  coils  at  the  bottom  of  the  tanks  to  preserve  the  contents  in  a  liquid 
state.  The  tops  of  the  .storage  tanks  are  open,  and  across  their  mouths  is  erected  a 
wooden  .stage  in  which  grilles  are  formed  on  to  which  the  barrels  are  emptied. 

The  next  stage  consists  in  thoroughly  drying  the  oil  so  as  to  meet  the  requirement 
for  success,  mentioned  above,  that  the  cataly.st  should  not  be  brought  at  any  time 
into  contact  with  raoi.sture.  The  desiccation  is  performed  in  two  stages.  The  oil  is 
first  pumped  from  the  storage  tanks  into  open  preliminary  heating  ves.sels  circular 
in  section  and  having  conical  bases.  These  vessels  are  fitted  with  mechanical  agitating 
gear  and  with  steam  heating  coils.  In  them  the  oil  is  freed  of  the  gi-eater  part  of  its 
moisture.  To  secure  the  final  and  complete  desiccation  the  oil  is  pumped  into  vacuum 
pans  consisting  of  circular  sectioned  vessels  with  domed  tops  and  conical  bases,  and 
containing  a  heating  coil  and  mechanical  stirring  gear.  The  domed  top  of  each  pan 
is  provided  with  an  inlet  connection  for  the  oil  and  a  connection  to  a  vacuum  pump. 
The  outlet  for  the  oil  is  through  a  cock  at  the  foot  of  the  conical  base.  Steam,  fluid 
level  and  vacuum  gauges,  and  thermometers  are  fitted  in  comiection  with  the  pans. 
The  oil  leaving  the  pans  is  now  ready  to  be  brought  into  contact  with  the  hydrogen 
in  the  autoclaves,  but  before  proceeding  to  de.seribe  these  we  will  deal  with  the 
preparation  of  the  catalyst. 

Preparation  of  the  Catalyst. 

The  catalyst  employed  in  the  Lane  process  is  finely  divided  metallic  nickel.  It 
is  received  at  the  works  in  the  form  of  nickel  sulphate  in  crystals.  The  first  step  in 
its  preparation  consists  of  making  a  solution  of  the  nickel  sulphate  and  another  solution 
of  sodium  carbonate.  This  is  done  in  the  two  tanks  B,  C,  respectively.  Each  of  these 
tanks  is  fitted  with  an  open  steam  jet  to  facilitate  the  preparation  of  the  solution. 
They  are  erected  over  a  third  tank  provided  with  means  for  mixing  the  two  solutions 
when  they  are  turned  into  it.  The  result  of  this  mixture  is  the  precipitation  of  insoluble 
nickel  carbonate  and  the  passage  of  sodium  sulphate  into  solution.  Previous  to  the 
admission  of  the  two  solutions  a  quantity  of  finely  divided  refractory  neutral  material 
is  placed  in  the  mixing  tank.  In  practice  this  material  is  usually  kieselguhr — that  is 
to  say,  infusorial  earth  consisting  of  siliceous  diatom  fossils.  Its  fimction  is  to  act 
as  a  carrier  for  the  nickel. 

The  mother  liquor,  the  precipitate  of  nickel  carbonate,  and  the  kieselguhr  are 
drawn  off  from  the  mixing  tank  and  piun])ed  througli  a  filter  press  of  the  type  described 
in  our  preceding  chapter.  AVhen  the  filtering  is  completed  the  nickel  carbonate  and 
the  kieselguhr  are  found  consolidated  on  the  filter  cloths  as  cakes.  These  cakes  are 
thoroughly  dried  in  hot-air  stoves,  and  thereafter  are  reduced  to  powder  by  means  of 
an  edge  runner.  The  carbonate  has  now  to  be  roasted  or  calcined  so  as  to  reduce  it 
to  the  form  of  oxide.  Thereafter  comes  the  very  delicate  operation  of  reducing  the 
oxide  to  the  metallic  form.  This  is  effected  bj-  heating  the  oxide  in  contact  with 
hj'diogen — which  must  be  quite  free  from  air — at  a  certain  temperature.     One  form 


110      THE   PRODUC'TIOX   AX'D  TREATMENT   OF   VEGETABLE   OILS 


of  the  apparatus  employed  is  contained  ^^•ithin  a  heat -insulated  vertical  ease  to  which 
the  pulverised  material  is  fed  automaticallj-  at  the  top.  while  the  hj-drogen  is  admitted 
at  the  foot.  Inside  the  case  there  is  provided  a  series  of  slowly  reciprocating  grids 
or  sieves.  The  movement  of  these  constantly  exposes  fresh  portions  of  the  substance 
to  the  action  of  the  hydrogen,  and  at  the  same  time  determines  the  rate  at  which  the 
substance  falls  through  the  case.  The  apparatus  is  heated  by  the  hydrogen  itself, 
the  gas  before  its  admission  being  heated  to  the  requisite  temperature  in  an  external 
superheater  or  stove.     In  this  jjarticular  form  of  reducing  apparatus  the  reduction 

of  the  oxide  to  the  metallic  form  is  effected 
in  the  lower  portions  of  the  case.  In  the 
ujjper  portion  the  material — fed  to  the  case 
in  the  form  of  the  carbonate — is  calcined 
to  the  oxide.  After  leaving  the  lowest  grid 
the  reduced  material  accompanied  by  the 
kie.selguhr,  must  not.  of  course,  be  permitted 
to  come  into  contact  with  the  air.  It  is 
therefore  caused  to  fall  into  a  tank  of  oil  of 
the  same  kind  and  quality  as  that  to  be 
hardened.  After  thorough  mixing  the  black 
oily  preparation  is  ground  to  a  suitable 
consistenc}^  and  is  then  finallj'  ready  for 
admission  to  the  autoclave  along  with  the  oil. 


The  Laxe  Autoclave. 
An  autoclave,  designed  according  to 
Mr.  Lanes  patents,  is  illustrated  in  section 
in  Fig.  71.  It  is  a  cylindrical  upright  vessel, 
closed  top  and  bottom,  and  surrounded 
by  an  outer  jacket  of  fire-brick  to  constitute 
a  flue  for  the  gases  of  a  separately  fired 
furnace.  The  upper  half  of  the  vessel  is 
occupied  by  agitating  gear  consisting  of  a 
series  of  square  beater  discs  A  mounted  on  a 
power-driven  vertical  shaft,  and  an  equal 
number  of  metal  plate  cones  B  formed  with 
square  holes  at  their  centres,  and  fixed 
relatively  to  the  walls  of  the  vessel.  The 
lower  half  is,  in  the  working  condition, 
occupied  by  the  oil  to  be  tieated  mixed  with  the  catalyst.  A  pump  C  draws  the  oil 
from  the  foot  of  the  vessel  and  discharges  it  continuously  on  to  the  uppermost  of  the 
cones  B.  Falling  from  this  on  to  the  first  of  the  beater  plates  A  it  is  shot  off  against 
the  walls  of  the  vessel,  and  is  discharged  through  the  opening  in  the  second  cone  on 
to  the  second  beater  plate.  Before  it  returns  to  the  bottom  half  of  the  vessel  the  oil 
is  thus  thoroughly  churned  up  in  the  atmosphere  of  lijdrogen  under  pressure  which 
fills  the  upper  half  of  the  vessel.  The  oil  and  catalyst  are  introduced  at  D  and  the 
hydrogen  at  E.  At  F  a  connection  to  a  vacuum  pump  is  provided  whereby,  as  a 
preliminary  to  the  introduction  of  the  catalyst  and  hydrogen,  the  air  in  the  vessel  can 
be  removed. 

It  has  been  found,  as  the  result  of  practical  experience,  that  the  oil  in  the  lower 
part  of  the  vessel  is  apt  to  suffer  from  being  exposed  too  long  in  contact  with  the  hot 


Lane  Autoclavf 


INSERT  FOLDOUT  HERE 


THE    HYDRO(iP:NATU)X    OR    HARDENING   OF    OILS 


111 


surrounding  walls.  To  overcome  this  Mr.  Lane,  in  his  most  recent  designs,  extends 
the  agitator  shaft  to  the  foot  of  the  vessel,  provides  it  with  a  beater  or  paddle,  and 
surrounds  it  with  a  cylindrical  jacket.  The  oil  is  thus  circulated  from  the  paddle  up 
the  annular  space  between  the  jacket  and  the  walls  of  the  autoclave,  and  down  again 
tlirough  the  jacket  to  the  paddle.  In  Plate  VI.  we  give  the  general  arrangement 
drawing  of  a  Lane  autoclave  provided  with  this  improvement. 

If  matters  are  properly  regulated  the  pressure  inside  the  autoclave,  as  the  hydrogen 
is  pumped  in.  is  seen  to  rise  at  first.     On  reaching  a  certain  point,  depending  upon 


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I'IG.  72. — Mr.  Howard  Lane's  Kxperimoiital  Oil-LlardeidiiK  Plimt. 

the  temperature  maintained  in  the  oil,  the  pressure  becomes  stationary,  indicating 
that  the  hydrogen  is  being  absorbed  by  the  oil  as  fast  as  it  is  pumped  in.  When,  by 
sampling,  the  hardening  is  judged  to  be  completed,  the  oil  is  drawn  from  the  autoclave 
thiough  the  pipe  D  (Fig.  71),  and,  as  indicated  on  the  engraving  (Fig.  70),  is  cooled 
and  filtered.  The  cooling  is  not  sufficient  to  sohdify  the  oil,  but  is  only  sufficient  to 
prevent  the  hot  oil  from  mining  the  cloths  of  the  filter  press.  In  the  filters  the  very 
hirge  bulk,  if  not  the  whole,  of  the  metallic  nickel  and  the  kieselguhr  is  held  back. 
The  cakes  left  on  the  cloth  are  waslied  and  freed  from  oil,  arc  broken  up.  and  are 
returned  to  the  catalyst  prei)aring  department,  where  the  material  is  made  ready  for 
further  use. 

In  Fig.  72  we  give  a  view  showing  the  interior  of  Mr.  Lane's  laboratory  at  A.shford 
with  the  experimental  oil-hydrogenising  plant.  In  the  middle  of  the  background 
the  autoclave  is  to  be  seen  with,  to  the  right,  the  coke  or  coal-fired  furnace  used  in 


112      THE   PRODUCTION   AXD   TREATMENT   OF   VEGETABLE   OILS 


conjunction  with  it.     In  the  foreground  to  the  right  we  have  the  cooler  for  the  hardened 
oil,  and  to  the  left  the  filter  press. 

Cost  of  Workesg  the  Process. 
The  following  estimate  of  the  cost  of  working  a  plant  having  a  capacity  of  1  ton 
of  oil  per  hour  is  based  on  figures  supplied  by  ilr.  Lane.  In  studying  the  figures  it 
should  be  noted  that  the  rates  charged  for  nickel  sulphate,  kieselguhr.  and  carbonate 
of  soda  are  not  necessarily  those  for  which  these  materials  could  be  bought  in  the 
present  abnormal  time.  On  the  other  hand,  the  price  set  against  the  hydrogen  is, 
owing  to  recent  improvements,  probablj'  in  excess  of  that  at  which  it  is  obtainable, 
even«nder  the  conditions  of  to-day.  In  the  second  place  it  is  to  be  noticed  that  the 
figures  relate  to  the  haixiening  of  linseed  oil.  Certain  oUs,  for  example,  whale  oil, 
require  more  hydrogen  to  harden  them  than  does  linseed.  Others,  such  as  cotton- 
seed oil,  require  less.  As  the  charge  for  hydrogen  is  the  heaviest  in  the  Ust.  the  question 
of  what  precise  oil  is  being  dealt  with  is  a  point  of  considerable  importance  in  its  Ijearing 
upon  the  working  costs.  The  onlj-  other  heavv'  item  in  the  list  is  that  set  against 
•  loss  of  catalyst."'  The  magnitude  of  this  figure  also  depends  upon  the  nature  of 
the  oil  being  hardened. 


I'ost  of  Hardening  1   Ton  of  Linseed  OH. 

Hydrogen :  3,530  cu.  ft.  at  if.  6hl.  per  1,000  cu.  ft. 

Loss  of  catalyst 

Fuel  for  Heating :  1  cwt.  coke  at  30«.  per  ton . . 

Power 

Steam  :  1,344  lb.  at  3s.  id.  per  ton 

Water :  41*0  cu.  ft.  at  IM.  per  1,000  cu.  ft 

Filter  cloths  :  1  yard  at  Is.  3(/.  per  yard 

Labour  (including  preparation  of  catalyst):  7  men  at  6'/.  per  hour 

Banning  repairs 

Total  

Nickel  sulphate  at  42«.  per  cwt.,  kieselguhr  at  17s.  i>er  cwt., 
carbonate  of  soda  at  55s.  per  ton. 


£  s. 
0  16 
0  14 


CHAPTER   XIV 
THE  GENERATION  OF  HYDROGEN  FOR  OIL  HARDENING  PURPOSES 

So  important  to  the  successful  working  of  the  hydrogenation  process  of  hardening 
oils  is  an  inexpensive  commercial  method  of  obtaining  pure  hydrogen  that  we  need 
make  no  excuse  for  devoting  a  separate  chajater  to  the  subject.  There  are,  of  course, 
various  methods  of  generating  hj'drogen  on  a  commercial  scale,  one  well-luiown  one 
being  the  Linde-Frank-Caro  process,  which  extracts  the  hydrogen  from  water  gas 
by  liquefying  the  nitrogen,  carbon  monoxide,  etc.,  in  a  liquid  air  condenser.  This 
process  is  worked  in  this  country  by  the  British  Oxygen  Co.,  Ltd.,  and,  we  understand, 
yields  a  gas  which  is  suitable  for  hydrogenating  oils. 

The  process  we  propose  here  to  deal  with  exclusively  is,  as  we  mentioned  in  our 
preceding  chapter,  that  which  has  been  develoijed  within  the  past  fourteen  years  by 
Mr.  Howard  Lane,  of  the  Laboratory,  Ashford,  Middlesex.  The  basis  of  this  process 
is  the  oxidation  of  metallic  iron  by  means  of  steam,  the  oxygen  oi  the  steam  entering 
into  union  with  the  iron,  and  the  hydrogen  being  set  free.  Proposals  on  this  basis 
have  been  numerous — probably  more  numerous  than  those  under  any  other  system 
of  producing  hydrogen — but  in  many  instances  success  with  Ihe  method  has  been 
confined  to  the  laboratory.  The  undoubted  commercial  success  which  Mr.  Lane  has 
achieved  with  the  process  is  due  very  largely,  but  not,  as  we  will  have  to  explain, 
wholly,  to  the  attention  which  he  has  given  to  the  design  of  the  details  of  the  plant 
used. 

The  iron,  under  the  Lane  system,  initially  .supplied  to  the  hydrogen  retorts  is 
calcined  spathic  iron  ore,  the  jjurest  form  in  which  ferrous  carbonate,  J'eCOg  occurs 
in  Nature.  This  substance,  when  subjected  to  heat,  speedily  parts  with  its  carbon 
dioxide,  and  becomes  converted  to  a  porous  mass  of  ferrous  oxide,  FeO.  So  converted 
it  is  packed  within  the  hydrogen  retorts.  The  working  of  the  process  calls  for  the 
alternate  reduction  of  the  ferrous  oxide  to  metallic  iron  by  means  of  a  combustible 
gas,  and  the  conversion  of  tliis  metallic  iron  back  to  ferrous  oxide  by  means  of  steam. 
The  combustible  gas  used  for  (he  reduction  may  in  a  small  plant  be  ordinary  town's 
gas,  but  on  a  large  scale  purified  water-gas,  generated  at  the  site,  is  undoubtedly  to 
be  preferred  on  the  score  of  economy.  When  water-gas  is  used  it  is  purified  by  the 
removal  of  the  sulphur  dioxide,  hydrogen  sulphide,  carbon  dioxide,  moisture,  and  other 
impurities,  which,  as  made  in  the  producer,  it  contains.  As  admitted  to  the  ferrous 
oxide  in  the  hydrogen  retorts,  it  therefore  consists  of  about  equal  quantities  of  hydrogen 
and  carbon  monoxide.  The  reduction  of  the  ferrous  oxide  to  metallic  iron  is  accom- 
plished at  the  expense  of  these  two  constituents,  which  are  converted  respectively  into 
moisture  and  carbon  dioxide.  The  reduction  being  complete,  the  supply  of  purified 
water-gas  is  shut  off  and  steam  at  a  low  pressure  is  admitted  to  the  retorts.  The  earlier 
portions  of  the  hydrogen,  which  immediately  starts  to  come  off,  are  sent  elsewhere 
than  to  the  hydrogen  holder,  for  they  are  impure  to  the  extent  that  they  carry  with 
them  the  reducing  gas,  the  water  vapour,  and  the  carbon  dioxide,  lingering  in  the 
retorts  as  a  result  of  the  previous  reduction  process. 

Three  practical  points  must  now  be  noted,  for  tiiey  lie  at  the  basis  of  Mr.  Lane's 
method  of  working.     In  the  first  place,  it  has  been  found  that  the  reduction  of  the 


114      THE   PRODUCTION   AXE)   TREAT.ArENT   OF   VEGETABLE   OILS 

material  in  the  retorts  occupies  about  twice  as  long  as  the  oxidation.  Accordingly 
Mr.  Lane  divides  his  retorts  into  three  sections,  two  of  which  are  "  reducing,"  while 
one  is  "  oxidising."  In  the  experimental  plant  at  Ashford  we  found  that  the  control 
valves  were  being  operated  everj"  ten  minutes,  so  that  each  section  of  the  retorts  was 
producing  hydrogen  for  ten  minutes  in  every  half  hour. 

In  the  second  place.  ^Ir.  Lane  has  found  a  difficulty  which  previous  workers  with 
this  process  have  also  met,  and  wluch  has  been  responsible  for  its  being  commercially 
impracticable,  or  for  its  being  deemed  so,  in  more  than  one  instance.  The  difficulty 
is  that,  after  a  time,  the  iron  gradually  loses  its  activity',  and  in  the  end  practically 
fails  to  react  with  the  oxygen  of  the  steam.  The  trouble,  Mr.  Lane  has  discovered, 
arises  from  the  fact  that  it  is  not  possible  entirelj'  to  free  the  water-gas,  or  other  reducing 
gas  used,  from  sulphur,  carbon  dioxide,  and  other  impurities.  The.se  impurities  either 
combine  with  the  iron  or  collect  within  its  pores,  so  reducing  and  finally  stopping,  its 
activity.  To  overcome  this  ^Ir.  Lane  arranges  that,  at  stated  intervals,  the  working 
of  the  retorts  is  interrupted  momentarily  while  air  is  passed  through  them  backwards. 
This  bums  out.  or  otherwise  removes,  the  impurities  collected  in  the  iron. 

Thirdly,  the  water-gas,  or  other  reducing  gas,  it  has  been  fomid,  must  considerably 
exceed  in  amount  that  theoretically  necessary  to  efiEect  the  reduction  of  the  iron  oxide 
in  the  retorts.  The  gas  leaving  the  retorts  during  the  reduction  period  is  thus  mialtered 
water-gas,  carrying  with  it  the  moisture  and  carbon  dioxide  resulting  from  the  oxidation 
of  a  portion  of  the  volume  entering  the  retorts.  This  gas  would  represent  a  con.siderable 
loss  but  for  the  fact  that,  after  removing  the  moisture  in  it,  it  may  be  deflected  and 
used  for  firing  the  retorts. 

Li  Fig.  70  (Chapter  XIII.)  the  general  arrangement  is  given  of  the  hjdrogen- 
generating  plant  attached  to  an  oil-hydrogenising  factorj'  erected  to  ilr.  Lanes  designs. 
The  plant  consists  of  tliree  principal  items,  namely,  (a)  a  hydrogen  retort  furnace 
containing  the  iron-working  .substance  which  is  alternately  oxidised  bj'  the  steam 
delivered  from  {b}  a  boiler,  and  reduced  by  the  products  delivered  from  (c)  a  water-gas 
generator.  Added  to  these  there  are  (d)  purifiers  for  the  water-gas,  and  for  the  hydrogen 
(c)  holders  for  the  two  gase^.  (/)  compressors  for  the  hj-drogen,  and  (g)  reservoirs  for 
the  storage  of  the  compressed  hydrogen. 

Water-gas  Generators  an'd  Pcrifif.rs. 

It  is,  we  tliink,  unnecessarj"  for  us  here  to  enter  into  a  description  of  the  water-gas 
generators  supplied  with  the  plant.  Although  they  embody  in  their  design  certain 
details  representing  improvements  of  ilr.  Lane's  own  invention,  they  are  in  principle, 
and  in  action,  similar  to  all  other  water-gas  generators.  Further  than  this  they  do 
not  form  an  essential  feature  of  the  plant,  for  other  combustible  gases — for  example, 
town  gas — can,  as  we  have  remarked,  take  the  place  of  water-gas.  It  is  sufficient  for 
us  to  say  that  the  generators  are  supplied  with  air  from  a  tuibine-driven  blower,  and 
with  steam  from  the  .same  boiler  as  that  supplying  steam  to  the  hydrogen  retorts. 
The  water-gas  generated  has,  on  the  average,  a  calorific  value  of  from  280  to 
300  B.Th.U.s,  and  in  the  raw  state  may  be  said  to  have  roughly  the  following  composi- 
tion : — Hydrogen,  49  per  cent.  ;  carbon  monoxide,  43  ;  methane,  J  ;  carbon  dioxide, 
4  ;  together  with  nitrogen,  sulphur  dioxide,  hydrogen  sulpliide,  moisture,  and  dust 
and  other  mechanical  impurities.  The  gas,  on  leaving  the  generators,  passes  through 
a  superheater,  where  jt  exchanges  some  of  its  heat  with  the  steam  flowing  from  the 
boiler  to  the  generators.  Thereafter  it  is  led  to  a  scrubber,  where  it  is  cooled  and 
washed  with  water  to  deprive  it  of  its  dust.     It  is  then  taken  to  a  gasholder. 

The  gas  as  required  is  withdrawn  from  the  holder  by  means  of  a  "  booster  "  or 


INSERT  FOLDOUT  HERE 


GENERATION  OF  HYDROGEN  FOR  OIL  HARDENING  PURPOSES      115 

compressor  and  passed  along  to  the  purifiers.  The  booster  is  driven  by  a  small  steam 
engine,  which  is  controlled  by  the  pressure  of  the  gas  in  such  a  way,  that  as  tlie  resist- 
ance of  the  purifiers  increases  so  does  the  pi'essure  of  the  gas.  A  by-pass  is  provided 
in  order  that  the  gas  may  be  sent,  if  necessary,  straight  to  the  purifiers  at  the  gasholder 
pressure.  This  is  sometimes  convenient,  as,  for  example,  when  the  booster  has  to  be 
cleaned  or  repaired  or  when  the  hydrogen  retorts  are  being  run  banked. 

The  water-gas  purifiers  for  the  installation  represented  in  Fig.  70  are  four  in 
number.  They  serve  in  the  usual  way  to  remove  the  sulphur  dioxide,  hydrogen 
sulphide,  carbon  dioxide,  moisture,  etc.,  from  the  water-gas.  They  are  controlled 
by  a  centre  valve  of  special  construction,  packed  with  hard  fat,  to  prevent  leakage, 
on  the  principle  of  the  Stauffer  gi'ease  ctip.  This  valve  is  actuated  in  such  a  way 
that  one  of  the  purifiers  is  always  in  reserve,  while  the  gas  passes  in  sequence  through 
each  of  the  remaining  three.  The  crudest  gas  always  enters  the  foulest  purifier,  and 
leaves  from  the  cleanest.  At  intervals,  the  foulest  producer  is  switched  off  for  cleaning 
and  recharging,  while  the  stand-by  purifier  is  brought  into  action  at  the  other  end. 
In  this  way  all  four  purifiers  are  cut  out  and  cleaned  in  turn  without  interfering  with 
the  continuous  purification  of  the  water-gas.  The  gas,  after  leaving  the  purifiers,  is 
ready  to  be  passed  into  the  hydrogen  retorts. 

Hydrogen  Retort  Furnaces. 

The  general  arrangement  of  the  Lane  hydrogen  retort  furnace  is  represented  in 
the  drawings  given  in  Plate  VII.  Before  describing  the  construction  and  mode  of 
action  of  the  furnace,  we  would  repeat  what  we  remarked  above,  namely,  that  it 
takes  twice  as  long  to  reduce  the  ferrous  o.xide  to  metallic  iron  with  the  water-gas  as 
to  oxidise  the  iron  with  the  steam.  In  other  words,  the  time  spent  in  preparing  a 
given  weight  of  material  for  the  production  of  hydrogen  is  twice  as  great  as  the  time 
occupied  in  the  succeeding  step  during  which  the  hydrogen  is  being  generated. 

The  furnace  con.sists,  primarily,  of  a  brickwork  casing  containing,  in  the  size 
illustrated,  thirty-six  vertical,  cast-iron,  pipe-like  retorts.  The  top  ends  of  the  retorts 
are  fianged  and  jirovided  with  covers  for  removal  when  the  retorts  have  to  be  recharged 
with  ferrous  material.  The  spent  material  is  removed  through  similar  covers  at  the 
foot  of  the  retorts.  The  thirty-six  retorts  are  arranged  in  two  groups,  each  containing 
two  rows  of  nine  retorts  each.  This  division  is  of  no  practical  significance.  What  is, 
however,  impoitant  is  the  division  of  the  thirty-six  retorts  into  three  groups  P,  Q,  R, 
each  grouj)  containing  three  of  the  retorts  in  each  longitudinal  row.  While  the  gi'oups 
P  and  Q  are  "  reducing,"  the  group  R  is  "  oxidising."  After  running  thus  for  a  certain 
length  of  time,  the  gi'oup  Q  is  changed  over  to  "  oxidising  "  and  the  gi'oup  R  to 
"  reducing,"  the  group  P  remaining  at  the  reducing  setting.  Thereafter  P  is  set  to 
oxidise,  and  Q  and  R  to  reduce.  In  this  way  the  generation  of  hydrogen — from  the 
oxidishig  group — is  made  continuous,  while  the  double  time  required  for  reducing  is 
allowed  to  each  group. 

In  order  to  facilitate  our  description,  the  three  groups  of  retorts  are,  in  the  diagram 
of  the  plant  given  in  Fig.  73,  repre.sented  as  three  .single  retorts  P,  Q,  R.  Across  the 
front  of  the  furnace  and  external  to  the  brickwork,  there  run  six  horizontal  pipes 

A,  B,  C,  D,  E,  F.  The  top  end  of  the  retort  P  is  connected  as  at  G  to  a  valve  H  on  the 
pipe  A,  and  the  bottom  of  the  same  retort  as  at  J  to  a  valve  K  on  the  pipe  F.  The 
top  and  bottom  ends  of  the  retort  Q  are  similarly  connected  to  valves  on  the  pipes 

B,  E,  respectively,  and  the  top  and  bottom  ends  of  the  retort  R  to  valves  on  the  pipes 

C,  D.     The  three  pipes  A,  B,  C  are  coimectcd  at  each  end  to  vertical  pipes  L,  M,  and 


110      THE   PRODITTIOX   -\XD   TREATMENT   OF   VEGETABLE   OrL'< 

the  three  pipes  D,  E.  F  to  two  other  vertical  pipes  X,  S.  The  valves  H,.  K  are  inter- 
coimected,  so  as  to  be  operated  together.  The  two  other  pairs  are  similarly  connected. 
The  pipe  X  is  connected  with  the  water-gas  supply.  With  the  valve  setting 
indicated  in  the  diagram,  the  retorts  P.  Q  are  receivmg  water-gas  from  the  left-hand 
portions  of  the  pipes  F.  E  respectively.  The  gas  rising  up  the  retorts  is  reducing  the 
ferrous  oxide  in  them,  and  with  the  moisture  and  carbon  dioxide,  resultuig  from  the 
reaction,  is  passing  away  by  the  left-hand  portions  of  the  pipes  A.  B  to  the  pipe  L. 
From  this  pipe  it  may  be  sent  wholly  into  the  furnace  for  heating  the  retorts — ^no 
other  fuel  being  necessary.     As  we  have  already  said,  it  is  not  practicable  to  work 


Gas  Pun  Fie  r 


Hydrogen 


73.    -Lhiifrram  of  the  Lane  Hvdrofjeu  Eetort  Kurnace. 


with  ju.st  sufficient  water-gas  to  reduce  the  charge  of  ferrous  oxide  in  the  retorts.  An 
excess  is  required,  but,  as  will  now  be  understood,  the  excess  amomit  in  Mr.  Lanes 
plant  is  subsequently  usefully  employed.  At  one  time  Mr.  Lane  utili.^ed  the  excess 
gas  passed  through  the  retorts,  partly  for  firing  the  furnace  and  partly  by  retummg 
it  to  the  reducmg  gas  purifiers,  as  indicated  in  the  diagram,  so  as  to  make  it  available 
for  a  .second  passage  through  the  retorts.  This  plan  has  been  given  up,  for  it  was 
fomid  that  the  volume  of  carbon  dioxide  coming  off  with  the  excess  gas  was  such  as 
seriously  to  overtax  the  capacity  of  the  purifiers.  Mr.  Lane  now  prefers  to  utilise 
tlie  excess  gas  either  wholly  for  firhig  puj-poses  or  partly  for  firing  and  partly  for 
estabhshmg  a  reducing  envelope  for  the  combustion  chamber  in  which  the  retorts  are 
set.  the  object  being  to  minimise  the  wear  of  the  brickwork. 


GENERATION  OF  HYDROGEN  FOR  OIL  HARDENING  PURPOSES     117 

The  pipe  M  is  connected  with  a  supply  of  steam,  ^^''ith  the  valve  setting  repre- 
sented in  the  diagram,  the  retort  R  is  receiving  steam  from  the  right-hand  portion  of 
the  pipe  C.  Tliis  steam  passing  downwards  becomes  decomposed,  oxidising  the  metallic 
iron  in  the  retort  and  setting  free  hjalrogen.  Tlie  hydrogen  leaving  the  bottom  of  the 
retort  reaches  the  right-hand  portion  of  the  pipe  D  and  so  passes  into  the  pipe  S, 
whence  it  is  conducted  to  a  purifying  plant  and  a  gasholder. 

It  will  thus  be  seen  that  simply  l^y  the  operation  of  two  of  the  three  connected 
pairs  of  valves,  every  ten  minutes  or  so,  the  plant  is  capable  of  giving  a  practically 
continuous  output  of  hydrogen  gas.  Two  practical  points  have,  however,  to  be  noted. 
hi  the  first  place,  when  any  one  of  the  retorts  is  changed  over  from  ""  reducing  "  to 
■■  oxidising,"  it  is  at  the  moment  of  the  change  filled  with  water-gas  carrying  a  certain 
percentage  of  moisture  and  carbon  dioxide.  The  first  portion  of  hydrogen  formed  is 
therefore  bound  to  be  contaminated  with  these  substances.  To  avoid  passing  this 
impure  gas  into  the  pipe  S,  it  is  arranged  that  the  valves,  while  they  can  be  operated 
simultaneously  in  pairs,  as  stated,  can  also  be  operated  separately.  Thus,  when  the 
reducing  period  in,  say,  the  retort  P  is  completed,  the  valve  H  is  operated  to  admit 
steam  to  the  top  of  the  retort,  while  the  valve  K  is  for  the  moment  left  untouched. 
The  steam  being  at  a  higher  pressure  than  the  water-gas,  passes  down  the  retort  and 
becomes  converted  to  hydrogen.  This  hydrogen  mixing  \^ith  the  water-gas  in  the 
retort  causes  the  latter  to  flow  back  into  the  pipe  F  and  the  pipe  N.  Tho  impure 
hj'drogen  then  passes  with  the  fresh  water-gas  into  the  retort  Q  and  the  retort  R — now 
set  for  reducing — and  is  therefore  not  wasted.  In  a  very  short  time  the  hydrogen 
generated  is  sufficiently  pure  to  permit  the  valve  K  to  lie  operated  so  as  to  allow  the 
retort  P  to  take  up  its  projjer  function. 

When  jjassing  from  ""  oxidising  '"  to  "  reducing,"  the  retort  is  at  first  filled  with 
pure  hydrogen.  This,  beyond  rei^resenting  a  small  waste,  is  of  no  significance,  as  the 
incoming  water-gas  will  merely  be  enriched  in  hydrogen  to  a  iDro^Jortionate  extent. 
The  pair  of  valves  can,  therefore,  be  operated  simidtaneously  when  the  change  from 
oxidising  to  reducing  is  being  made. 

In  the  second  place,  as  we  have  already  said,  the  ferrous  material,  unless  revivified 
in  some  way,  very  soon  loses  its  activity  and  fails  to  decoraijose  the  steam.  This, 
phenomenon,  Mr.  Lane  has  found,  is  due  to  the  dejiosition  on  the  iron  of  sulphur  and 
other  impurities  which,  even  with  very  careful  purification  of  the  water-gas,  accumulate 
in  the  retorts  during  successive  periods  of  reduction.  The  practical  cure  devised  for 
the  trouble  is  at  intervals  to  blow  air  through  the  retorts,  so  as  to  burn  out  the  accumu- 
lated impurities.  To  effect  this,  the  three-way  cock  T.  Fig.  73,  is  turned  to  shut  doM'n 
the  supply  of  water-gas  and  to  open  a  branch  pipe  leading  from  a  fan  or  other  blower. 
The  three-way  cock  U  on  the  excess  water-gas  outlet  pipe  is  also  turned  so  as  to  close 
this  pipe  and  open  a  branch  pipe  leading  to  the  atmo.sphere.  The  air  from  the  fan, 
if  the  retort  valves  are  placed  in  the  "  reducing  "  position,  then  passes  up  through  the 
retorts,  and  with  the  sidphur  dioxide  and  other  products  derived  from  the  impurities 
in  the  ferrous  material  blows  off  into  free  space. 

The  action  of  the  wat*r-gas  on  the  ferrous  oxide  during  the  reducing  pei-iod 
results,  as  we  have  said,  in  the  excess  water-gas  passing  off  being  laden  with  moisture 
and  contaminated  with  carbon  dioxide.  For  efficient  combustion  that  portion  of  the 
water-gas  used  for  firing  the  furnace  should  not  lie  heavily  laden  with  moisture. 
Accordingly,  somewhere  at  or  near  the  ]ioint  V  (Fig.  73),  the  excess  water-gas  is  taken 
oil  to  a  condenser  and  returned.  The  po.sition  of  the  condensers  relatively  to  the 
furnaces  is  indicated  in  the  plan  given  in  Fig.  70. 

With  a  little  study  of  the  drawuigs  given  in  Plate  \M1.  the  lines  on  which  the 


lis      THE  PRODUCTION    AND  TREATMENT   OF  ^^:GETABLE   OILS 


GENERATION  OF  HYDROGEN  FOR  OIL  HARDENING  PURPOSES     llf) 

design  of  tlie  hydrogen  retort  furnace  is  carried  out  in  practice  will  now  readily  be 
understood.     Several  points,  however,  may  usefully  be  called  attention  to. 

The  retorts  are  of  cast  iron  and  are  9  in.  in  internal  diameter,  li  in.  thick,  and 
9  ft.  9  in.  long.  Each  fits  into  a  base  socket  and  seats  therein  on  a  joint  of  asbestos. 
The  three  groups  of  retorts  P,  Q,  R,  as  sho\^ii  in  the  plan,  are  each  divided  into  two 
equal  sub-groujjs.  Six  pipes — see  the  side  elevation — run  horizontally  along  the  two 
sides  of  the  furnace  exterior.  To  each  of  these  jsipes  the  top — or  the  bottom — ends 
of  a  .sub-group  of  the  retorts  are  connected.  Each  of  the  six  pipes  on  one  side  of  the 
furnace  is  connected  to  the  corresjjonding  pipe  on  the  other  side  by  a  horizontal  pipe 
extending  across  the  front  of  the  furnace.  This  front  pipe  in  each  instance  is  inter- 
rupted at  a  suitable  point  to  couple  up  with  the  two  flanges  F,  G  of  the  revensing  cock — 
see  Fig.  74.  The  top  ends  of  the  twelve  retorts  in  each  group  are  thus  connected  to 
one  such  reversing  cock,  while  the  bottom  ends  of  the  same  twelve  retorts  are  connected 
to  a  second  reversing  cock  situated  directlj^  in  line  with  and  below  the  first,  as  shown 
in  the  front  elevation  in  Plate  VII.  In  front  of  the  six  front  pities  referred  to,  and 
comiected  to  the  flanges  H,  J  of  the  reversing  cocks,  lie  the  six  pipes  represented  in  the 
diagram  Fig.  73,  at  AB — F.  The  vertical  pipes  L,  M,  N,  S  in  the  diagram  are  clearly 
shown  in  Plate  VII.,  the  only  point  to  notice  being  that  in  practice  the  pipes  L  and 
M  are  respectively  united  to  the  pipes  N  and  S,  and  are  not  separated  therefrom.  A 
blank,  however,  is  interposed  between  the  flanges  of  each  pair. 

With  the  cock  plugs  turned  anticlockwise  through  about  30  degrees  from  the 
position  shown  in  the  plan,  Fig.  74,  the  ports  A  and  B  are  opened,  and  reducing  gas  is 
sent  upwards  through  the  retorts.  A  60-degree  movement  of  the  plug  in  the  clockwise 
direction  from  this  position  opens  the  ports  A,  C,  and  causes  steam  to  pass  downwards 
through  the  retorts.  It  will  be  noticed  that  a  fourth  and  fifth  port  are  formed  in  the 
body  of  the  reversing  cock,  and  that  when  the  cock  is  in  the  central  position  shown 
in  the  engraving  these  two  ports  are  open  to  one  another.  The  flange  K  in  each  of 
the  three  lower  reversing  cocks  is  open  to  the  atmosphere.  In  the  three  upper  cocks 
it  is  connected  by  a  vertical  pipe  to  a  horizontal  pipe  extending  across  the  top  front 
edge  of  the  furnace  casing.  At  one  end  of  this  horizontal  pipe  an  ejector  is  fitted. 
By  turning  the  reversing  cocks  into  the  central  position,  and  setting  the  ejector  to 
work,  air  is  drawn  upwards  through  the  retorts  for  the  purpose  of  burning  out  the 
impurities  which,  in  time,  accumulate  on  the  ferrous  material.  The  use  of  an  ejector 
in  this  way  instead  of  a  fan,  as  indicated  in  Fig.  73,  has  certain  obvious  advantages, 
and  is  now  Mr.  Lane's  standard  practice. 

It  will  be  noticed  from  the  front  elevation  in  Plate  VII.  that  the  spindles  of  the 
three  upper  reversing  cocks  are  extended  down  to  the  level  of  the  lower  cocks  so  that 
the  handles  of  each  pair  are  brought  close  together.  The  two  cocks  of  each  pair  can 
thus  be  moved  simultaneously  as  when  passing  from  '"  oxidising  "'  to  "  reducing," 
or  separately  as  when  the  impure  hydrogen  has  to  be  blown  momentarily  into  the 
water-gas  pipes  at  the  commencement  of  the  oxidising  periods. 

During  the  normal  running  of  the  furnace  the  excess  water-gas  is,  as  we  have 
said,  made  use  of  in  part  for  firing  the  retorts.  At  the  commencement  of  a  run  a 
valve  near  the  reducing  gas  inlet  is  closed  and  another  one  on  the  same  pipe  is  opened. 
This  enables  the  furnace  to  be  fired  with  water-gas  taken  direct  from  the  supply  main. 
These  means  are  also  called  into  use  during  the  slack  periods,  when  the  generation  of 
hydrogen  is  interrupted.  The  firing  may  he  reduced  during  such  periods,  but 
it  is  not  desirable  that  it  should  be  totally  stopped.  Generally  Mr.  Lane 
recommends  that  the  plant  should  be  run  continuously  day  and  night  ;  but  if  this 
is   impracticable,   he   recommends   that  the  temperature  of  the  furnace  should   be 


120       THE   PRODUCTION   AND   TREATMENT   OF   VEGETABLE   OILS 

kept  as  nearlj-  equal  as  possible,  for  this  reduces  the  wear  and  tear  on  the  furnace 
work. 

The  plant  illustrat-ed  in  Plate  VII.  gives  an  output  of  about  3.500  cub.  ft. 
of  hydrogen  per  hour.  For  smaller  plants  having  hourly  outputs  of,  say.  250  to 
1,000  cub.  ft.  ordinary  town's  gas  is  conveniently  used  for  i-educing  the  ferrous  material 
and  for  firing  the  retorts.  The  small  experimental  plant  at  ilr.  Lanes  laboratory — 
see  Fig.  75 — is  operated  in  this  manner.  But  for  plants  above  such  outputs  up  to  the 
largest  size — say.  10,000  cub.  ft.  per  hour — it  is  distinctly  economical  to  install  with 
them  their  own  gas  producers.  The  puritj'  of  the  gas  generated  by  Mr.  Lanes  process 
is  guaranteed  by  him  to  be  from  99  to  991  per  cent.  In  practice,  however,  this,  we 
are  informed,  is  exceeded,  the  purity  reaching  as  high  as  99|  per  cent.  The  purification 
of  the  hydrogen  after  it  leaves  the  retorts  con-^ists  of  passing  it  through  a  scrubljer. 


Fig.  75.    -Experliucntal  llyilrogen  Plant. 


where  it  is  washed  with  water,  and  then  through  ijuiifiers  in  which  lime  is  employed 
to  remove  minute  traces  of  such  impurities  as  sulphur.  After  purification  the  gas 
is  passed  into  a  holder,  whence  it  is  withdrawn  as  required,  compressed  to  a  pressure 
of  anjiihing  up  to  3,000  lb.  per  square  inch,  and  stored  in  a  batteiy  of  weldless  steel 
cylinders.  From  these  it  is  allowed  to  expand  at  the  proper  pressure  into  the  oil 
hydrogenising  autoclaves. 

The  cost  of  producing  hydrogen  by  this  method  is  difiicult  to  state,  for  it  depends 
almost  entirely  upon  the  local  prices  of  fuel  and  labour.  It  may.  under  normal  con- 
ditions, be  expected  in  the  average  case  to  varj-  from  3s.  dd.  to  7s.  Gd.  per  1. 000  cub.  ft. 
In  some  cases,  however,  it  may  be  as  low  as  2s.  (id.,  or  less  actually  than  the  cost  of 
town's  gas  in  the  London  area. 

Before  leaving  this  account  of  Mr.  Lanes  apparatus,  it  ma}'  perhaps  be  stat«d 
that  his  oil  hydrogenating  plant  was  the  outcome  of  the  success  which  attended  his 
efforts  to  produce  pure  hydrogen  in  large  quantities  under  commercial  conditions. 
It  would  appear  likely  that  in  the  near  future  Mr.  Lanes  hydrogenising  plant  may  be 
applied  to  substances  other  than  the  classes  of  oil  named.     A  veiy  promising,  and,  if 


GENEHATIUN   UF   HYDROGEN  FOR   OIL   HARDENING  PURPOSES     121 

successful,  a  very  important  application  of  it,  lies  in  its  use  for  hydrogenising  mineral 
oils.  It  may  yet  be  possible  to  synthetase  petrol  by  its  means.  Mr.  Lane  has  already 
succeeded  in  devising  apparatus  whereby  he  can  cause  hydrogen  to  combine  with 
acetylene,  CM.,,  to  produce  ethylene,  C.Hj,  a  gas  which  can  be  liquefied  at  a  tempera- 
ture of  0"  C.  by  a  pressure  of  41  atmospheres,,  and  which  possesses  great  energy  as  a 
motive-power  fuel. 


CHAPTEE    XV 
THE   MAXITACTURE   OF   SOAP 

SoAP-siAKDTG  provides  a  very  important  industrial  outlet  for  the  employment  of 
vegetable  oils,  although,  of  course,  the  soap  maker  also  uses  large  quantities  of  animal 
oils  and  fats. 

Chemistry  of  Soap-m.\ki>g. 

As  we  remarked  in  a  preceding  chapter,  fatty  vegetable  and  animal  oils  may  be 
considered  as  consisting  essentially  of  a  glycerine  part  and  an  acid  part.  To  the  soap 
maker  the  acid  part  is  the  portion  of  prime  importance.  Li  the  process  of  manufacture 
the  acid  part  is  caused  to  unite  with  an  alkali,  the  glycerine  pai't  beuig  in  general  left 
over  as  a  bj^-product.  It  is,  of  course,  a  very  valuable  bj'-product,  particularly  at 
the  present  moment,  and,  as  a  consequence,  we  fuid  it  an  increasingly  common  practice, 
particularly  on  the  Continent,  to  recover  the  glycerine  from  the  oil  by  special  processes 
in  deglj^cermising  works,  which  carry  on  their  industry  quite  apart  from  that  of  the 
soap  maker.  Under  these  conditions  the  soap  maker  works  with  the  by-product 
of  another  industry,  namely,  the  fatty  acid  stock  discarded  from  the  deglycciinising 
works.  With  the  plant  employed  in  the  latter  works  we  do  not  propose  in  this  chapter 
to  deal.  Our  attention  will  be  devoted  solely  to  the  manufacture  of  soap  from 
undivided  oils  and  fats. 

When  an  acid  (sa3',  sulphuric  acid)  is  caused  to  act  on  a  metal  (.say,  copper)  a  salt 
(copper  sulphate)  is  produced.  If  the  acid  is  the  fatty  acid  contamed  in  a  vegetable 
or  animal  oil  or  fat,  and  if  the  metal  is  either  sodium  or  potassium,  the  salt  produced 
is  known  as  a  soap,  a  hard  soap  if  sodium  is  the  metal  and  a  soft  soap  if  it  is  potassium. 
Other  soaps  are  possible  and  are  made.  Thus  practical  uses  are  found  for  soaps 
obtained  by  substituting  for  the  alkali  metals  either  iron,  nickel,  cobalt,  zinc,  magne- 
sium, aluminium,  copper  or  mei'curj'.  These  "  soaps  "  are,  in  general,  in.soluble  in 
water,  and  are  used  for  such  purposes  as  waterproofing  agents  for  canvas,  as  "  driers  " 
to  be  added  to  boiled  oil  or  varni.sh,  as  constituents  of  anti-fouling  compositions  for 
ship  bottoms  and  so  on.  We  need  say  nothing  more  about  the  manufacture  of  these 
"  soaps  "  than  that  they  are  made  similarly  to  ordinary  soap,  or  by  emplonng  such 
soap  as  a  basis  for  decompo.sition. 

Pure  hard  soap  is  thus  the  fatty  acid  salt  of  the  metal  sodium.  It  should  be 
perfectly  neutral.  It  contains  none  of  the  glycerine  of  the  oil  or  fat  from  which  it 
was  formed.  Pure  soft  soap  is  the  neutral  fatty  acid  salt  of  the  metal  potassium. 
In  its  commercial  production,  practice  is  diAnded  as  to  whether  or  not  it  should  be 
freed  from  the  glycerine  of  the  oil  or  fat  u.sed  in  its  manufacture.  It  seems  to  be 
established  that  if  the  glycerine  is  removed  the  quality  and  ajjpearance  of  the  soap 
suffer,  and  accordingly  it  is  quite  a  common  practice  to  allow  the  gljxerine  to  remain 
in  the  .soap. 

Soap  Boiling. 
There  are  two  distinct  methods  of  making  hard  or  soda  soap,  namely,  the  hot 
and  the  cold  processes.     The  latter  has  a  restricted  application,  and  is  not  of  sufficient 


THE    MANUFACTURE    OF    SOAP 


123 


importance  to  be  considered  here.     Under  the  hot  process  the  sodium  is  presented 

to  the  fatty  acid  of  the  oil  or  fat  in  the  form  of  an  aqueous  solution  of  caustic  soda, 

NaOH.     This  solution  is  added  gradually  to  the  oil  or  fat  in  a  soap  kettle,  the  whole 

being  kept  boiling.     A  typical  soap  kettle,  made  by  W.  J.  Eraser  &  Co.,  Ltd.,  of 

Dagenham,  Romford,  Essex,  is  illustrated  in  Fig.  76.     It  is  built  up  of  mild  steel 

plates,  and  contains  several  separate  steam  heating  coils  and  a  swivelhng  outlet  pipe 

with  a  chain  hoist,  whereby  the  soap,  when  formed,  may  be  drained  off.     At  the  foot 

of  the  kettle  an  outlet  is  provided  for  the  liquor  separated  from  the  soap.     The  size 

of  these  kettles  may  vary  from  8  ft.  diameter  b}^  8  ft.  deep  to  13  ft.  diameter  by  14  ft. 

deep,  and  their  capacity  from  5  to  25  tons.      The  boiling,  it  will  be  seen,  is  carried 

out  at  atmospheric  pressure.     This  is  the  common  practice.     A  recent  improvement 

consists   in    conducting    the   operation 

under  about   100  lb.  of  pres-sure  in  a 

closed  vessel  some  4  ft.  in  diameter  by 

8  ft.  high. 

The    soda    solution    is     added 

gradually  to  the  oil  or  molten  fat  in 

the  kettle.      If  it  is  added  too  rapidly 

the  saponification  process  is  retarded. 

On  the  other  hand,  the  total  amount 

of  soda  solution  mixed  with  the  oil  or 

fat  must  be  more  than   the   quantity 

theoretically    necessary    completely    to 

saponify  the  substance.      An  excess  is 

required,    because    if     the     theoretical 

amoimt  only  is  used  a  point  is  reached 

at  which  the  soap  formed  up  to  that 

point,  the  oil  or  fat  yet  remaining  to  be 
saponified  and  the  alkaline  solution 
corresponding  to  this  quantity  of  oil  or 
fat  will  establish  a  balance.  Fig.  76.— Soap  Kettle— Fraser. 

When  the  boiling  operation  is  completed,  the  kettle  contams,  first,  soap,  and 
secondly,  water,  in  which  are  dissolved  the  surplus  caustic  soda  and  the  glycerine 
set  free  from  the  oil  or  fat.  Various  impurities  from  the  caustic  soda  and  some  animal 
or  vegetable  tissue  or  other  non-saponifiable  matter  from  the  oil  or  fat  used  will  also 
be  present.  The  mass  in  the  kettle,  for  the  moment,  is  a  more  or  less  clear  homo- 
geneous substance.     Soap,  however,  is  scarcely,  if  at  all,  soluble  in  a  solution  of  salt. 

Accordingly,  dry  common  salt  is  shovelled  into  the  kettle,  and  the  whole  contents 
are  thoroughly  boiled  up  again.  The  salt  entering  into  solution  causes  the  soap  on 
cooling  to  separate  out  on  the  surface.  The  aqueous  Hquor  below  the  soap  containing 
caustic  soda,  salt  and  glycerine  in  solution  is  run  off  through  the  bottom  of  the  kettle 
and  sent  to  the  glycerine  recovery  department.  The  soap  layer  is  now  boiled  up 
again  with  water  and  again  salted  out.  The  aqueous  liquor  is  run  off  and  the  boiling 
and  salting  process  repeated  a  third  time.  Thereafter,  the  soap  left  when  the  third 
liquor  is  drained  off  is  given  a  fuial  boilmg  with  water  in  order  to  hydrate  it  to  the 
correct  degree.  It  is  not,  however,  subsequently  salted,  but  is  allowed  to  stand  for 
some  few  days  imdisturbed.  At  the  end  of  this  time  it  is  fomid  to  have  separated 
into  three  layers.  At  the  foot  there  is  a  small  layer  of  alkaline  liquid.  Intermediately, 
and  amounting  to  about  a  third  of  the  whole  ma.ss  in  the  kettle  is  a  layer  of  dark- 
coloured  soap  called  tlic  "  nigj-e."    This  substance  contains  traces  of  caustic  soda  and 


124       THE   PRODUCTION  AND   TREATMENT   OF   VEC4ETABLE   OILS 

salt  solution,  and  owes  its  darl<  colour  to  the  ]3resenoe  in  it  of  soaps  of  iron,  co}>per. 
and  other  metals.  Above  this  is  the  "'  neat  "  soap  which,  being  practically  pure  and 
neutral,  is  in  a  condition  to  be  used.  The  "  nigre,""  after  removal,  is  boiled  and  salted 
and  otherwise  treated  for  the  recovery  of  its  valuable  portions. 

Crutching. 
The  "  neat  "  soap  is,  as  we  have  said,  in  a  condition  to  be  used.     Li  nearh'  every 
case,  however,  it  is  passed  into  a  "  crutching  "  machine,  wherein  colouring,  scenting 

or  other  matter  is  added  to  it. 
Among  such  other  matter  are 
various  "  fillei-s,"  such  as  clay, 
talcum,  chalk,  barytes,  seed  husks, 
asbestos,  magnesium  salts,  and 
starch.  These  substances  increase 
the  weight  of  the  soap,  and  are 
frequently  regarded  as  adulterants. 
In  some  cases  the  soap  is  "  filled  " 
with  either  the  borate,  carbonate 
or  sihcate  of  soda.  These  fillers 
have  themselves  distinct  cleansing 
propeities,  so  that  their  addition 
is  not  strictly  to  be  classed  as 
adultei'ation. 

A  crutching  machine  made 
by  E.  Timmins  &  Sons,  Ltd., 
■Runconi,  is  shown  in  Fig.  77. 
It  consists  of  a  double  -  walled 
steam-jacketed  cylindiical  vessel 
containing  a  vertical  power-driven 
shaft,  from  which  four  or  more 
beater  arms  extend  horizontally. 
Six  or  more  fixed  arms  springing 
from  the  inner  surface  of  the 
vessel  co-operate  with  the  rotating 
a  r  m  s  .        Very    frequently    t  h  e 


1*          ^    idiO 

1 

Fig.  77. — Crutching  Machine — Timmins. 


crutchers  are  arranged  in  paLivs,  as  showii  in  Fig.  78,  where  a  twin  set,  made  by 
R.  Daglish  &  Co.,  Ltd.,  of  St.  Helens,  is  represented.  The  practice  here  indicated  of 
driving  the  machines  by  an  attached  single-cylinder  steam  engine  is  quite  usual,  for 
it  permits  the  exhaust  steam  from  the  driving  engine  readily  to  be  utilised  in  the 
jackets  of  the  crutchers.  In  Fig.  79  we  illustrate  in  cross-section  a  steam-driven 
crutcher  made  by  George  Scott  &  Son  (London),  Ltd. 


Soap  Frames. 

The  soap,  while  still  hot.  is  run  out  of  the  crutching  machines  into  moulds  or 
"  frames,"  where  it  is  allowed  to  cool  and  set.  A  typical  soap  frame,  made  by  Messrs. 
Timmins,  of  Runcorn,  is  showni  in  Fig.  80.  These  frames  have  removable  sides,  so 
that  they  may  be  knocked  down  when  the  soap  has  solidified.  They  are  frequently 
made  of  cast  iron,  but  mild  steel  is  now  being  commonly  em])lo}ed.  The  capacity 
of  each  is  anything  from  3  to  10  cwt.  of  soap. 


THE    MANUFACTURE    OF    SOAP 


1^5 


Slabbing  and  Cutting. 
The  slab  of  soap,  as  taken  from  the  frame,  has  to  be  cut  up  into  bars,  and  these 
bars  have,  commonly,  to  be  again  cut  into  tablets.  The  original  slab  is  first  subdivided 
into  several  slabs  of  lesser  thickness,  and  each  of  these  is  cut  up  into  bars  by  means 
of  a  machine,  such  as  that  .«ho'^^^l  in  Fig.  81.  The  machine  illustrated  is  made  by 
Messrs.  Timmins,  of  Runcorn,  and  has  a  flat  table  whereon  the  divided  slab  rests. 
By  means  of  a  hand-wheel,  crank  discs,  links,  levers,  and  a  guided  cros.spiece,  the  slab 
is  pushed  forward  beneath  a  fixed  bridge,  from  which  a  number  of  equally  spaced 
piano  wires  extend  vertically  to  the  surface  of  the  table.     Means  are  provided  for 


Via.  "S. — Twill  Crutchiii^  Machines — Daglish. 

adjusting  the  tension  in  the  wires.  The  bars  thus  formed,  if  they  are  to  be  further 
divided  into  tablets,  are  taken,  separately,  to  a  cutting  machine  of  the  type  illustrated 
in  Fig.  82.  The  machine  illustrated  is  made  by  Messrs.  Daglish,  of  St.  Helens.  In 
the  block  of  wood  A  a  number  of  vertical  saw  cuts  are  formed,  while  along  the  top  a 
vee-sectioned  recess  is  provided  for  the  reception  of  the  bar  of  soap.  The  frame  B  is 
pivoted  on  a  rod  C  at  the  back  of  the  machine  and  carries  a  number  of  equally  spaced 
piano  wires,  which  register  with  the  saw  cuts  in  the  block  A.  With  the  bar  of  soap  in 
place  the  frame  is  simply  pressed  dowii  by  hand. 


Drying. 
cut  into  tablets  contains  round  about  33  per  cent,  of  water, 


The  soa[)  as  thu 
and  for  this  reason  is  comparative!}'  soft  and  sticky. 


It  is  customary,  therefore,  to 


12G      THE  PRODUCTION  AXD  TREATMENT  OF  \'EGETABLE   OILS 


subject  it  to  a  dr\ing  treatment,  in  oi-der  to  form  a  crust  of  hard  soap  roun'l  the  soft 
interior.     By  so  doing  further  evaporation  from  the  body  of  the  soap  is  retarded  and 

the  weight  is  preserved.  In  addition,  the 
dn-ing  of  the  crust  is  eseential,  if,  as  is 
frequently  the  case,  the  tablets  after  cut- 
ting, have  to  be  pressed.  It  is  impossible 
to  carry  out  this  pressing  if  the  criLst  is  not 
hai-d,  for  the  sticky  soap  is  bound  to  adhere 
to  the  press  dies.  Practice  as  regaid-; 
diying  has  recently  undergone  a  change. 
Formerly,  the  soap  was  dried  simply  by 
l^lacing  it  in  a  room  heated  by  steam  pijjes 
or  coils.  The  improved  modern  method 
makes  use  of  a  warm  air  blast.  Apparatus 
for  this  purpose,  made  by  Messrs.  Eraser,  of 
Dagenham.  Essex,  is  illustrated  in  Fig.  83. 
It  consists  simply  of  a  steam  heater  through 
which  air  is  driven  by  an  attached  fan 
into  a  wrought  iron  easing  provided  with 
hinged  doors  and  containing  several  tiers 
of  galvanised  iron  wire  trays  for  holding 
the  soap. 

STASrPIXG. 


Fig.  79. — S^team  Driven  Crutcher — -Scott. 

their  api>earance.  A  hand-machine  for 
this  purpose,  made  by  ilessrs.  Daglish. 
of  St.  Helens,  is  illustrated  in  Fig.  84. 
This  machine  is  capable  of  dealing  with 
either  1-lb.  or  }  lb.  tablets.  It  con- 
sists of  two  balanced  fly-wheels  united 
b3'  a  crosspiece  with  handle,  and 
operating,  through  an  arm.  a  phmger. 
which  works  within  a  sleeve  pivoted  at 
its  lower  end  to  the  frame  of  the 
machine.  The  bottom  of  th?  mould 
box  is  loose,  and  is  designed  to  rise  on 
the  upstroke  of  the  plunger,  so  as  to 
eject  the  soap  from  the  mould.  The 
tablet  is  frequently  stamped  twice,  once 
on  each  face. 

CHIPriNG    AXD    MlLUXG. 

Soaps  prepared  as  described  above 
are  suitable  for  many  purposes,  notablv 
for  lamidry  and  similar  work.  They  are 
liable,  however,  with  time  to  lose  weight 
by  shrinkage  and  othenvise  to  deteriorate 


The    rough    tablets    are,    after    being 
dried,  verj-  commonly  stamped  to  improve 


Fig.  hi.— Soap  Frame — Tin.- 


For  the  production  of  the  best  quality  of 
toilet  soaps,  the  process  known  as  milling  is  resorted  to.     The  first  step  in  this  process 


THE   MANUFACTURE    OF   SOAP 


127 


is  to  reduce  to  cliips  the  soap  as  taken  from  the  frames.     Tlie  slabs  are  first  cut  into 
bars  and  paiiially  dried.     Thereafter,  they  are  taken  to  a  chipping  machine,  such  as 


Fig.  si. — Slab  Cutting  Machine — Timmiiis. 

that  shown  in  Fig.  85,  which  illustrates  a  double-sided  machine  made  by  Joseph  Baker 
&  Sons,  Ltd.,  of  Willesden  Junction,  London.     The  bars  of  soap  are  placed  in  the 


Fk;.  Sli. — Bar  Cutti 


shoots  shown,  so  that  their  ends  may  come  in  contact  with  the  blades  of  the  rapidly 
revolving  cutters  disposed  within  the  casings.  The  chips  fall  from  the  foot  of  the 
casings  on  to  trays  supported  on  the  angle-iron  runners  shown.  The  thickness  of  the 
chip.s  can  be  regulated  to  suit  requirements. 


128       THE   PRODUCTION   AND  TREATMENT   OF   VEGETABLE   OILS 

The  chips  are  next  dried  until  thej'  contain  round  about  10  per  cent,  of  water. 
For  this  operation  the  driving  jilant  ilhistrated  in  Fig.  83  is  suitaljlc.     Colouring  and 


Fig.  S3. — Soap  Di-yin^sr  Plant — -Fraser. 

scenting  materials  are  then  added  to  tlie  dried  chiiJs,  and  the  whole  is  ground  up  in 

a  toilet  soap  mill.  A  machine  of  this 
description  made  by  INIessrs.  Baker,  of 
\\'illesden  Junction,  is  illustrated  in 
Fig.  86.  This  mill  consists  of  five 
granite,  or  sj'^enite,  rollers  very  carefully 
ground  to  truth.  The  rolls  are  31  in. 
long,  the  four  lower  rolls  being  13  in. 
in  diameter,  and  the  top  roll  19  in. 
The  lowest  roll  and  the  third  roll  run  at 
a  relatively  slow  speed.  The  second 
and  fourth  rolls  run  at  about  twice 
this  speed,  while  the  top  roll  runs  at 
about  four  times  the  speed  of  the 
lowest  roll.  A  double  hopper  is  arranged 
in  front  of  the  rolls.  The  soap  chips  are 
fed  into  the  lower  division  of  this 
hopper  and  pass  thence  to  be  ground 
between  the  differentially  moving  rolls. 
As  the  material  comes  round  the  fifth 
roll,  it  is  scraped  off  into  the  upper 
division  of  the  hopper.  Wien  the 
whole  batch  has  accumulated  in  this 
division  a  shutter  at  the  foot  is  with- 
dra\\n.  and  the  charge  allowed  to 
return  to  the  lower  division  for  a 
second  pass  through  the  mill.  From 
..  four  to  eight  passages   are  frequently 

■''"  ""  '■  given    to    the    material,    the    number 

depending  upon  the  quality  desired  in  the  resulting  product.     At  the  end  of  the  last 
pass  the  soap  is  scraped  off  in  the  form  of  thin  ribbons  from  the  back  of  the  top  roller. 


Fig.  S4. — Stamiiing  Macliiiic- 


The  manufacture  ok  soap 


129 


I'l'-i.  i)(j. — MilliiiL'  Mauhiiie—  Baker. 


130      THE    PRODUCTION   AXD   TREATNIEXT   OF   \T:GETABLE   OILS 


THE    MANUFACTURE    OF    SOAP  131 

The  mass  of  ribbons  is  next  transferred  to  a  squeezing  machine  or  "  plodder," 
of  which  an  example  made  by  Messrs.  Fraser,  of  Dagenham,  Essex,  is  illustrated  in 
Fig.  87.  This  machine  squeezes  the  soap  through  a  perforated  die  plate  A,  so  that  it 
comes  out  in  the  form  of  small  round  threads.  Thereafter,  the  die  plate  is  removed 
and  the  material  is  once  more  passed  through  the  machine.  As  it  passes  through  the 
die  plate  B  at  the  end  of  the  cone-like  mouth-piece,  the  soap  is  squeezed  into  a  solid 
bar,  which  is  received  on  the  table  C  and  thence  passed  to  a  cutting  and  stamping 
machine.  The  squeezing  of  the  soap  through  the  die  plates  is  effected  by  a  short 
worm  rotating  at  about  20  revolutions  per  minute  at  the  foot  of  the  hopper, 
and  arranged  coaxially  with  the  conical  mouthpiece.  This  worm  is  fed  with  soap 
from  the  hopper  by  the  action  of  a  finger  shaft  D  within  the  hopper,  and  driven  by 
gearing  from  the  worm  shaft.  A  heating  jacket  is  provided  round  the  worm,  to  faciU- 
tate  its  work  on  the  soap.  When  the  machine  is  stopped  at  the  end  of  a  run,  the  cone 
is  still  filled  with  soap.  To  remove  this  the  cone  is  hinged  so  that  it  may  be  swung 
downwards  and  clamped  within  the  bracket  E.  The  die  plate  B  having  previously 
been  removed  together  with  the  cover  or  cap,  which  holds  it  in  place,  the  hand-wheel  F 
is  operated  so  that  the  piston-like  head  formed  on  it  may  rise  within  the  cone  and  eject 
the  soap  upwards.  The  output  of  this  machine  is  from  3  to  5  cwt.  per  hour.  A 
modification  is  sometimes  to  be  found  in  use.  In  this  the  squeezing  machine  is  com- 
bined with  the  mining  machine.  It  is  very  doubtful  if  such  a  combination  is  as  satis- 
factory as  keeping  the  two  machines  apart. 


CHAriER    XVI 

GLYCERINE  RECOVERY  AXD  REFINING  AND  THE  SPLITTING  OF  OILS 

Glycerine  and  a  fattj-  acid  are,  as  we  have  remarked,  the  two  essential  parts 
of  every  animal  or  vegetable  oil  or  fat.  It  must  not,  however,  be  thought  that  such 
an  oil  or  fat  consists  simply  of  a  mixture  of  these  two  substances.  In  reality  neither 
glycerine  nor  fatty  acid  should  exist  separately  as  such  in  a  neutral  oil  or  fat.  If 
they  do,  particularly  if  free  fatty  acid  is  present,  we  have  a  sign  that  the  oil  or  fat  has 
suffered  some  decomposition. 

The  matter  may  be  put  with  advantage  in  a  popular  May  without  introducing 
cumbersome  chemical  fonuulse.  A  molecule  of  oil  consists  of  a  molecule  of  glycerine — 
less  an  atom  of  hydrogen  and  an  atom  of  oxygen — and  a  molecule  of  fattj'  acid — less 
an  atom  of  hydrogen.  It  will  be  noticed  that  the  missing  atoms  together  constitute 
a  molecule  of  water.  If  this  molecule  of  water  can  be  added  to  the  oil  under  suitable 
conditions  then  the  molecules  cf  glycerine  and  fatt}-  acid  will  be  made  complete  and 
will  separate  from  one  another.  If,  instead  of  water,  HOH,  we  add  a  molecule  of 
caustic  soda,  NaOH,  the  glycerine  is  again  made  complete,  but  the  fatty  acid  molecule 
receives  a  sodium  instead  of  a  hydrogen  atom,  and  separates  not  as  a  fatty  acid,  but 
as  a  soap.  Lime,  Ca(0H)2,  acts  similarly  and  jields  glj'cerine  on  the  one  hand,  and 
a  lime  soap,  insoluble  in  water,  on  the  other.  Caustic  potash,  KOH,  also  acts  in  the 
same  manner,  giving  glycerine  and  soft  soap  ;   and  so  on  for  other  hj'droxides. 

The  splitting  up  of  vegetable  and  animal  oils  into  glj-cerine  and  fattj-  acid  forms 
an  important  branch  of  industrj-,  and  is  carried  out  in  a  variety  of  ways.  Thus  it 
can  be  directly  effected  by  subjecting  the  oil  to  the  prolonged  action  of  superheated 
steam — a  fact  which  explains  wh}-  animal  and  vegetable  oils  are  not  so  popular  as 
mineral-oils  for  lubricating  parts  of  machine ly  and  engines  subjected  to  high  tempera- 
tures. The  .splitting  up  can  also  be  achieved  bj-  treating  the  oil  with  lime,  drawing 
off  the  glycerine  thus  set  free,  and  treating  the  lime  soap  further  with  sid^ihuric  acid 
to  convert  the  soap  into  fatty  acid  with  the  liberation  of  calcium  sidphatf .  There 
are  several  other  important  proces.ses  of  carrying  out  the  work.  Their  object  is,  of 
course,  to  obtain  the  valuable  glycerine  bj-  a  direct  method,  and  to  recover  the  fatty 
acid  as  a  Ijy -product,  which  maj-  be  sold  to  the  soap  maker  or  candle  maker. 

The  soap  maker,  as  we  have  stated,  very  frequently  prefers  to  work  with  the  ■^^hole 
oil  (  r  fat  and  not  with  the  fatty  acid  by-prcduct  of  the  de-glyceriiiising  works.  He 
prefers  to  do  so  because  the  glyceiine  thus  comes  under  bis  own  control,  and  forms  a 
valuable  adjunct  to  his  business.  Apart  from  this  it  is  beUeved  that  the  recover}-  of 
the  glj^cerine  is  more  complete  if  performed  after  the  soap  has  been  made  than  it  is 
if  the  oil  or  fat  is  spht  beforehand.  Again,  the  recover}-  of  the  glycerine  if  perfoimed 
at  the  soap  works  enables  the  soap  maker  also  readily  to  recover  the  salt  \^hich  he 
uses  to  separate  the  soap  in  the  kettle.  Finallj-,  it  is  stated  that  the  production  of 
soap  from  fatty  acid  stock  requires  much  more  skill  thin  is  necessarj-  if  an  unsplit  oil 
or  fat  is  used.  In  this  chapter  we  propose  to  deal,  first,  with  the  recover}'  of  the 
glycerine  .set  free  as  a  result  of  the  soap  making  process  ;  secondly,  with  the  splitting 
of  oils  and  fats  as  carried  out  in  de-glycerinisiug  works  and  elsewhere  and  finally  with 
the  refining  of  crude  glycerine. 


GLYCERINE  RECO\rERY  AND  REFINING  AND  SPLITTING  OF  OILS     133 

Glycerine — or  glycerol,  to  give  the  perfectly  pure  body  its  proper  scientific  name — ■ 
is  present  in  all  vegetable  and  animal  oils  and  fats  to  the  extent  on  the  average  of 
about  10  per  cent,  by  weight.  It  is,  of  course,  known  to  the  public  as  a  colourless, 
odourless,  sweet-tasting,  syrupy  liquid,  but  its  fluidity  appears  to  be  due  to  its  impurity. 
Pure  glycerine  is  a  solid  at  all  temperatures  up  to  about  17'  C,  at  which  point  it  melts. 
In  its  common  form  it  is  a  liquid  weighing  about  1}  times  the  weight  of  an  equal  volume 
of  water.  It  is  combustible,  and  burns  to  water  and  carbon  dioxide.  Its  boiling- 
point,  like  that  of  water  and  other  liquids,  depends,  of  course,  upon  the  pressure  to 
which  it  is  subjected.  At  normal  atmospheric  pressure  it  boils  at  290°  C.  and  in 
so  doing  suffers  some  decomposition.  Its  distillation  cannot  therefore  be  satisfactorily 
performed  except  under  a  reduced  pressure.  At  an  absolute  pressure  of  1  lb.  per  square 
inch  it  boils  at  210°  C,  and  at  one-tenth  of  a  pound  per  square  inch  it  boils  at  163^  C. 
It  can  be  mixed  with  water  in  any  degree,  but  is  insoluble  in  benzene,  carbon  disulphide, 
and  oils.  The  two  first -named  substances,  as  we  have  seen,  readily  dissolve  oil.  They 
will  not,  however,  dissolve  glycerine  when  separated  from  the  fatty  acid  combined 
with  which  it  forms  an  oil.  On  the  other  hand,  glycerine  itself  is  a  very  ready  solvent 
for  a  large  number  of  substances,  rivalling,  and  at  times  surpassing,  water  in  this 
respect.  Among  such  substances  are  many  metallic  salts  and  halogen  compounds, 
certain  metallic  oxides,  caustic  alkaUes.  and  various  metallic  soaps,  that  is  to  say, 
soaps  in  which  the  sodium  or  potassium  is  replaced  by  other  metals  such  as  iron, 
magnesium  and  calcium. 

Recovery  of  Crude  Glycerine  from  Soap  Works  Spent  Lyes. 

All  the  facts  we  have  just  mentioned  have  an  important  bearing  on  the  problem 
of  recovering  the  glycerine  from  the  "  spent  lyes  "  of  a  soap  works.  The  spent  lyes 
run  off  from  a  kettle  in  which  hard,  i.e.,  soda,  soap,  has  been  made,  consist  of  water 
in  which  various  bodies  are  dissolved,  and  with  which  small  proportions  of  various 
insoluble  substances  are  mixed.  They  contain  first  of  all  nearly  the  whole  of  the 
glycerine  combined  in  the  original  oil  or  fat  from  which  the  soap  has  been  made.  This 
constituent  may  amount  to,  say,  about  6  or  7  per  cent,  of  the  whole,  and  is,  of  cour.se, 
dissolved  in  the  water.  Next  in  imi)ortance  comes  the  salt — sodium  chloride — which 
in  the  soap-making  process  is  thrown  into  the  kettle  to  cause  the  soap  to  rise  and 
separate  itself  from  the  rest  of  the  contents.  This  salt  is  dissolved  in  the  solution 
of  gljcerine  and  water,  and  is  present  in  sufficiently  large  quantity  to  make  its  recovery 
from  the  lye  an  important  element  in  the  economy  of  the  soap  works.  The  lye  also 
contains  in  solution  a  small  amount  of  the  caustic  soda  used  to  saponify  the  oil  or 
fat,  for  it  is  impossible  to  work  with  just  that  amount  of  soda  which  is  necessaiy  to 
effect  the  saponification  of  the  given  quantity  of  oil  or  fat.  The  excess  soda  is  dis.solved 
in  the  glycerine-salt  solution.-  The  glycerine,  salt,  and  soda  are  the  three  chief  consti- 
tuents of  the  aqueous  lye,  and  would  be  the  only  constituents  if  everything  were 
theoretically  perfect.  In  practice,  however,  the  oil  or  fat,  the  salt  and  the  soda,  are 
never  pure  or  anything  like  it.  The  oil  or  fat  is  sure  to  contain  mucilage  and  albuminous 
matter,  while  the  soda  and  salt  between  them  contribute  various  chemical  impurities, 
such  as  metallic  salts  and  sulphates,  sulphides,  and  other  bodies.  These  pass  into  the 
lye  unaltered,  or  in  combination.  In  addition,  the  lye  nearly  always  contain-  a  small 
amount  of  soap,  for  sodium  soap  is  not  completely  insoluble  in  salt  water. 

The  spent  lye  is  thus  a  very  complex  substance.  For  many  years  it  was  regarded 
as  practically  useless,  it  being  held  that  the  cost  and  trouble  of  recovering  the  glycerine 
from  it  were  too  great  to  make  the  undertaking  pay.  Glycerine  in  those  days  was  in 
very  limited  demand.     With  the  invention  of  djTiamite  and  nitro-glycerine,  substances 


134      THE   PRODUCTION   AND   TREATMENT   OF   "\'EOETABLE   OILS 

which  to-day  afford  by  far  the  greatest  outlet  for  glycerine,  the  circumstances  were 
altered,  and  great  attention  came  to  be  jiaid  to  the  recovery  of  glycerine  by  soap  makers. 


"The    EHGiNctr."  Swain    Sc. 

Fio.  88. — Single  Effect  Vacuirm  Evaporator  for  Concentrating  Crude  Glycerine — Scott. 

Its  enhanced  value  then  made  it  profitable  to  devote  considerable  pains  to  its  recover^', 
and  to  this  was  added  as  an  incentive  the  practicability  of  recovering  the  salt  simul- 
taneously from  the  lyes.  To-day,  soap  makers,  as  a  ride,  have  modified  their  soap- 
making  practice  to  the  end  that  the  glycerine  may  be  recovered  more  readily  and  in 


GLYCERINE  RECOVERY  AND  REFINING  AND  SPLITTIN(i  OF  OILS     135 

a  purer  form  than  used  to  he  the  case.  In  particular  thej'  have  largely  abandoned 
the  use  of  certain  crude  saponifying  chemicals  in  favour  of  others  which  are  less  likely 
to  contribute  undesirable  impurities  to  the  lye. 


Flu.  S!l.- 


■Iliit  N'aeuum  Kvapomtm  tor  I'oucentriitiiiL; 
(ilj'cerine — Scott. 


Purifying  the  Lye. 

The  first  step  in  the  treatment  of  the  lye  is  to  acidify  it.  This  is  commonly  done 
by  running  it  into  a  tank  and  adding  hydrochloric  acid  to  it.  The  result  of  this  is 
that  the  free  caustic  soda  is  converted  into  common  salt  and  water,  while  any  soap 
dissolved  in  the  lye  is  decomposed  into  free  fatty  acid  and  common  salt.  S'multa- 
neously,  iron  sulphate,  aluminium  sulphate  or  common  ahun  is  added  to  the  lye. 
This  combines  with  the  free  fatty  acid  to  form  a  metallic  soap,  which,  being  insoluble, 
is  precipitated.     At  the  same  time,  these  chemicals  coagulate  and  precipitate  the 


136      THE   PRODUCTION   AND   TREATMENT   OF   VEGETABLE   OILS 


albuminous  and  other  colloidal  matter  in  the  lye,  just  as  they  do  in  the  case  of  their 

application  to  sewage  purification. 

The  treated  lye  is  then  i:)assed  through  a  filter  press  and  sent  into  a  second  tank. 

It  consists  now,  primarily,  of  water, 
glycerine  and  common  salt,  with  the  excess 
of  hydrochloric  acid  and  ferric  or  other 
sulphate  added  during  the  pieceding  treat- 
ment as  im2:)iirities.  Caustic  scda  is,  there- 
fore, carefully  added  to  it  until  it  becomes 
neutral  by  the  conversion  of  the  hydro- 
chloric acid  into  salt.  The  soda  also  acts 
on  the  ferric  or  other  sulphate,  the  result 
of  the  reaction  being  the  precipitation  of 
insoluble  iron  hydroxide  and  the  formation 
of  sodium  sulphate  which  passes  into 
solution  in  the  glycerine,  salt  and  water 
lye.  The  liquid  is  now  once  again  filtered 
and  is  passed  into  a  third  tank,  whence  it 
is  withdrawn  as  required  for  further  treat- 
ment. 

CONCENTEATIOX. 

This  further  treatment  consists  of  con- 
centrating the  liquid  by  the  evaporation  of 
its  water  portion.  As  the  concentration 
j^roceeds  the  salt,  or  the  bulk  of  it,  is  thrown 
out  of  solution  and  can  ultimately  be 
collected  and  used  again  in  the  soap  kettle. 
It    is    clear   that    all    the    salt   camiot   be 

removed  fiom  the  Ij'e  simjjly  by  evaporation  of  the  water.     Even  if  the  evaporation 

were  carried  to  completion  there  would   still  remain  a  fair  amount  of  salt  dissolved 

in  the  glycerine  left  behind.      As  a  fact,  the  liquid  resulting  fiom  the  evaporation 

is  what  is  known  as  crude  glycerine,  and  at  the  best  consists  of,  say,  80  per  cent,  of 

pure  glycerine  and  about  10  per  cent,  of 

salt,   the    remainder    being    water    and 

certain  chemical  imj^urities. 

The  plant  emjjloyed  for  evaporating 

the  treated  lye  at  one  time  consisted  of 

fire-heated  pans.     These  were  succeeded 

by  open  air  steam-heated  ves.sels.      The 

fact,  however,  that   high    temperatures 

or  prolonged  heating  reacted  inifavour- 

ably      on      the     glycerine,     was     soon 

recognised,    and    as    a    result,    vacuum 

evaporators  were  introduced.    These  not 

only  effect  the  evaporation  quickly  and 

at  a  reduced  temperature,  but  economise  fuel  by  permitting  exhaust  steam  to  be 

used  for  their  heating. 

A  tyi^ical  examj^le  of  a  modern  single  effect  vacuum  evaporator  for  the  recovery 

of  crude  glycerine,  as  made  by  George  Scott  &  Son  (London),  Ltd.,  Kingsway  House, 

Kingsway,  W.C.  2,  is  illustrated  in  Figs.  88  and  89.     The  liquid  having  been  filtered 


Fig.  90.. 


-Removing  Salt  from  a  Yaciuim 
Evaporator. 


Fig.  91. — Automatic  Salt  Dischargin 


GLYCERINE  RECOVERY  AND  REFINING  AND  SPLITTING  OF  OILS     137 

from  the  second  treatment  tank  A  into  the  third  tank  B  is  drawn  up  by  the  vacuum 
into  the  evaporator  C — Fig.  88.  This  vessel  is  provided  with  a  tube  plate  near  the 
top  and  near  the  bottom.  Between  these  plates  extend  a  number  of  vertical  tubes 
up  which  the  licpiid  is  caused  to  rise.  The  space  outside  the  tubes  and  between  the 
tube  plates  is  filled  with  heating  steam.  The  tubes  are  of  two  diameters,  and  are  so 
arranged  as  to  promote  a  vigorous  and  uniform  circulation  without  recourse  to 
mechanical  means.  It  is  essential  to  have  a  good  circulation  in  these  evaj^orators, 
for  otherwise  the  salt,  as  the  evaporation  proceeds,  \^ill  deposit  on  the  interior  of  the 
tubes  and  restrict  or  choke  them,  instead  of  falling,  as  it  is  intended  to  do,  into  the 
conical  end  of  the  evaporator  below  the  lower  tube  plate.  A  good  circulation  may 
furtlier  be  relied  upon  materially  to  reduce  the  chance  of  the  liquid  "  frothing  "  and 
boiling  over.  To  eliminate  all  danger  from  this  cau.se,  however,  Messrs.  Scott  fit  a 
"■  catch-all ""  D  or  trap  with  internal  baffles  to  intercept  the  overflow  and  return  it 
to  the  evaporator. 

The  vaporising  space  above  the  upper  tube  plate  is  connected  by  a  pipe  to  a 
vacuum  pump  E  of  special  design.  The  pump  plunger  works  beneath  a  body  of  water 
in  a  tank  :  by  the  displacement  of  this  water  the  steam  is  drawn  over  from 
the  evaporator  and  delivered  through  a  jet  condenser.  The  lower  conical  end  of  the 
evaporator  is  in  communication  with  a  vessel  F,  into  which  the  salt  falls  as  the 
evaporation  proceeds.  When  the  salt  vessel  is  full  it  is  isolated  from  the  evaporator  by 
means  of  a  sluice  valve.  The  further  precipitation  of  salt  is  allowed  to  accumulate  in 
the  conical  end  of  the  evaporator  until  the  vessel  Fhas  been  cleared.  Before  the  door  of 
the  salt  vessel  is  opened  a  valve  on  the  pipe  G  is  ojierated  to  place  the  vessel  for  a  short 
time  in  communication  with  the  vacuum  inside  the  evaporator.  The  salt  resting  on 
a  metallic  filter  inside  the  vessel  is  thus  drained  of  nio.st  of  the  liquid  adhering  to  it. 
which  liquor  is  returned  to  the  evaporator.  Steam  is  now  turned  on  into  the  salt 
vessel,  so  as  to  wash  and  dry  the  salt  as  far  as  possible.  The  washings  are  returned 
by  the  pipe  G  to  the  evaporator.  The  door  of  the  vessel  can  then  be  opened — see 
Fig.  90 — the  salt  removed,  and  the  vessel  once  again  put  into  communication  with  the 
evai^orator.  The  salt  thus  removed  is  comparatively  dry,  and  can  be  re-used 
immediately  in  the  soap  kettles. 

For  large  plants  an  automatic  arrangement  is  frequently  fitted  by  Messrs.  Scott, 
in  place  of  the  vessel  F,  whereby  the  salt  is  discharged  continuously.  This  device  is 
illustrated  in  Fig.  91.  Its  construction  is  simple  and  obvious.  In  this  case  the  salt 
is  discharged  moist  and  saturated  with  liquor,  and  is  immediately  dried  and  washed 
in  a  centrifugal  machine.  In  Fig.  92  we  give  a  view  of  a  large  glycerine  recovery 
plant  capable  of  dealing  with  500  tons  of  spent  lye  per  day.  This  plant  is  fitted  with 
the  automatic  salt-extracting  arrangement  referred  to,  and  witii  mechanical  means 
for  convejdng  the  salt  to  and  from  the  centrifugals. 

The  evaporation  of  the  liquor  and  the  extraction  of  the  precij^itated  salt  are 
proceeded  with  until,  as  we  have  said,  the  liquor  shows  a  concentration  representing 
an  80  per  cent,  content  of  glycerine.  This  condition  is  judged  by  noting  the  tempera- 
ture of  the  liquor  in  the  evaporator,  for  as  the  water  is  eliminated  the  boiling-point 
of  the  liquor  left  rises.  At  any  given  pressure  above  or  below  atmospheric,  there  is  a 
definite  boiUng  point  for  each  and  every  strength  of  liquor.  In  the  neighbourhood  of 
80  per  cent,  concentration  the  boiling-point  ri,ses  bj'  about  1°  C.  for  each  1  per  cent, 
increase  in  the  concentration.  It  may  be  remarked  that  even  at  atmospheric  pressm-e 
the  boiling  point  of  an  80  per  cent,  solution  of  glycerine  in  water  is  no  more  than  about 
120°  C,  and  under  a  vacuum  it  is,  of  course,  still  less.  Hence  exhaust  steam,  if  available, 
will  in  most  cases  be  quite  sufficient  for  heating  the  evaporators. 


GLYCERINE  RECOVERY  AND  REFININC  AND  SPLITTING  OF  OILS     139 

When  the  concentration  has  reached  the  desired  degree  the  vacuum  pumi)  and 
jet  condenser  are  closed  down,  and  the  ciude  gl\'cerine  is  lun  off  into  stoie  tanks. 
A  fresh  cliarge  of  liquor,  \\hich  in  the  meantime  has  been  treated  chcmical'y  in  the 
mamier  described  above,  is  immediately  introduced  into  the  evaporator. 

The  apparatus  described  so  far  is  of  the  "  single  effect  "  tyjie,  and  is  suitable  for 
use  where  the  supply  of  exhaust  steam  is  abundant.     Where  it  is  not,  and  where  fuel 


Fig.  93. — Double-effect  Vacuum  Evaporator  tor  Concentrating  Crude  CJlycerine. 

is  expensive,  it  is  usual  to  employ  a  double  effect  evaporating  plant  of  the  type  illus- 
trated in  Fig.  93.  In  such  a  ca.se  live  steam  is  supplied  to  the  first  evaporator  onlj'. 
This  evaporator  is  worked  at  a  pressure  not  much  less  than  atmospheric,  so  that  the 
vapour  developed  in  it  may  be  .sufficiently  hot  to  be  utilised  as  the  heating  fluid  for 
the  second  evaporator.  This  second  evaporator  works  at  a  high  vacuum.  The  liquor 
receives  a  preliminary  concentration  in  the  first  evaporator,  and  is  then  passed  on 
for  final  treatment    ii  the  .-^ecoiid.     I'stuillv  nearly  all,  if  not   the  whole  of  the  .salt  is 


140      THE   PRODUCTIOX  AXD  TREATiMENT   OF   VEGETABLE   OILS 


deposited  in  the  salt  vessel  of  the  second  evaporator.  The  first,  however,  is  also  fitted 
\\ith  a  salt  vessel,  so  that  either  evajjorator  may  be  run  on  the  single-effect  jirinciple 
should  repairs  to  one  unit  or  anj'  other  cause  render  this  desirable.  The  jilant  shown 
in  Fig.  92 — already  referred  to — consists  of  four  double-effect  evaporators. 

The  presence  of  the  salt  in  soap  makers"  waste  Ij-es  is  undoubtedly  a  disadvantage 
when  it  comes  to  the  problem  of  recovering  the  glycerine.  The  crude  gljxerine.  as  we 
have  said,  is  bound  to  retain  a  considerable  percentage  of  the  salt.  Even  the  subse- 
quent refining  of  the  glycerine  by  distilla- 
tion may  not  entirely  eliminate  it.  With 
tlie  increased  demand  for  pure  glycerine 
which  has  arLsen  with  the  development  of 
high  explosives,  more  and  more  attention 
has  come  to  be  paid  to  alternative  methods 
of  obtaining  the  crude  product,  methods 
which  do  not  involve  the  glycerine  being 
brought  into  contact  with  salt  at  anj'  point 
or  with  more  than  a  small  amount  of  any 
other  chemicals. 

The  Splittixg  of  Oils  and  Fats. 

The  "  splitting  ''  of  oils  and  fats  can 
be  performed  in  several  ways.  Roughly 
stated,  the  object  aimed  at  is  to  make  each 
molecule  of  oil  take  i\p  a  molecule  of  water, 
so  as  to  form  a  molecule  of  glycerine  and  a 
molecule  of  free  fatty  acid,  or,  to  speak  scien- 
tifically, to  ■'  hydrohse  "  the  oil.  We  have 
already  mentioned  in  a  previous  chapter, 
that  the  hj'droh'^^is  of  an  oil  once  started 
is  liable,  if  \^'ater  be  present,  to  continue 
automatically  until  a  very  considerable  pro- 
portion of  the  oil  is  converted  into  a  mixture 
of  glycerine  and  free  fatty  acid.  In  the  case 
of  palm  oil,  for  example,  the  prevention  of 
hj'droh^sis  is  very  difficult  if  not  impossible. 
We  are  now  dealing  with  an  aspect  of  affairs 
in  which  the  encouragement  of  hj^drolysis 
may  be  said  to  be  the  direct  object  in  view. 


04.- — <  111  and  Fat  Splitting  Autoclaves 
Scott. 


Autoclave  Proces.'*. 

The  two  principal  methods  of  .sphtting  oils  are  the  autoclave  method  and  the 
Twitchell  process.  A  pair  of  autoclaves  for  oil  or  fat  splitting  by  ^Messrs.  George  Scott 
&  Son  is  illustrated  in  Fig.  i)4.  These  are  simjjly  cylindrical  heating  vessels  and  as 
shown,  are  usually  not  provided  with  agitating  gear.  The  fat  or  oil  is  introduced 
into  the  autoclave  together  with  1  or  2  per  cent,  of  some  base,  such  as  lime,  magnesia, 
barium  oxide  or — very  commonlj'  to-day — zinc  oxide.  Steam  at  a  pressure  of.  say, 
150  lb.  is  then  admitted  to  the  autcclave.  the  pressure  being  maintained  for  from  four 
to  six  hours.  The  small  amount  of  chemical  base  used  is  sufficient  to  start  the  decom- 
position of  the  oil  or  fat  into  glj-cerine  and  a  lime,  magnesia,  etc.,  soap.     This,  once 


GLYCERINE  RECOVERY  AND  REFINING  AND  SPLITTING  OF  OILS     141 

started,  induces  hydrolysis,  and  the  rest  of  the  oil  or  fat  taking  up  water  from  the  steam 
becomes  converted  to  glycerine  and  fatty  acid. 

Thereafter  the  contents  of  the  autoclave  are  treated  with  a  small  amount  of  acid 
to  decompose  the  soap  formed  by  the  base  into  fatty  acid  and  a  lime,  magnesium  or 
other  salt.  The  fatty  acid  and  the  glycerine  are  then  separated  by  taking  advantage 
of  their  difference  of  specific  gravities.  The  glycerine  contains  much  water — it  is 
known  at  this  stage  as  "  sweet  waters  " — and  is  filtered  and  concentrated.  The 
concentration  is  effected  in  an  evajiorator  similar  to  that  described  above  in  connection 
with  the  treatment  of  soap  makers'  lyes.  No  salt  extracting  details  are,  however, 
jirovided,  for  no  salt  is  preseiit  in  the  liquor.  About  95  j'er  cent,  of  the  oil  or  fat 
originally  introduced  into  the  autoclave  is  on  the  average  converted  by  this  method, 
although  at  times  as  much  as  98  jjer  cent,  can  be  completely  split.  The  remainder 
passes  away  unchanged  with  the  fatty  acid. 

The  Twitchell  Process. 

An  important  alternative  method  to  the  above  is  Twitchell"s  process.  If  oleic 
acid — a  fatty  acid  occurring  in  many  oils  and  fats — and  benzene,  naj^hthalene,  or 
certain  other  bodies  are  mixed  and  treated  with  sulphuric  acid  a  certain  compound 
results,  known  as  Twitchell's  reagent  This  compound  may  popularly  be  said  to  have 
the  power  of  fermenting  oils  and  fats  when  boiled  with  them  at  atmospheric  pressure, 
for  it  readily  hydrolises  them  into  glycerine  and  fatty  acid.  The  fact  that  the  action 
is  satisfactorily  effected  at  atmospheric  pressure  gives  the  Twitchell  process  certain 
advantages  over  the  autoclave  method.  In  particular,  it  permits  the  process  to  be 
conducted  in  wooden  vessels. 

In  Fig.  95  we  give  the  general  arrangement  of  a  splitting  plant  on  the  Twitchell 
system,  erected  by  Messrs.  George  Scott  &  Son.  To  secure  success  with  this  process 
the  oil  or  fat  must  first  be  freed  from  iron,  lime,  and  other  impurities.  Accordingly, 
it  is  initially  boiled  with  sulphuric  acid  in  the  lead-lined  wooden  vat  B.  The  coagulated 
impurities  sink  to  the  bottom,  and  the  clean  oil  is  drawn  off  from  a  point  near  its 
surface  level  and  is  pas.sed  into  the  "  saponifying  vessel  "'  C.  Here  it  is  mixed  with 
from  one-third  to  one-half  of  its  weight  of  distilled  water  drawn  from  the  tank  A,  and 
with  from  J  to  2  per  cent,  of  the  Twitchell  reagent.  The  charge  is  then  agitated  and 
boiled  for  a  period  extending  up  to  twenty-four  hours  by  means  of  steam  delivered 
direct  into  it  from  a  perforated  coil  within  the  vat.  A  close-fitting  wooden  cover  is 
provided  for  the  vat  which,  while  allowing  steam  to  escape,  prevents  the  free  access 
of  air  to  the  charge.  This  is  desirable,  because  the  hot  fatty  acid  set  free  from  the 
oil  is  liable  to  darken  in  colour  in  the  presence  of  air  in  excess.  When  the  boiling  is 
completed  the  charge  is  allowed  to  stand  until  the  fatty  acid  portion  rises  to  the  top 
and  the  glycerine  and  water  portion  sinks  to  the  bottom.  The  latter  is  drawn  off  into 
the  tank  D,  where  it  is  neutralised  with  lime  water  and  allowed  to  settle.  The  fatty 
acid  portion  may  be  boiled  up  again  with  water  to  extract  the  last  traces  of  free  glycerine. 
Any  sulphuric  acid  in  it  is  neutralised  with  barium  carbonate,  the  addition  of  which 
to  the  charge  results  in  the  precipitation  of  barium  sulphate.  The  neutralised  glycerine 
water  is  pumped  through  the  filter  press  E  into  the  tank  F.  The  separated  fatty  acid 
is  drawn  off  from  the  tank  C  by  the  pump  G.  From  the  tank  F  the  glycerine  water 
is  passed  into  the  evaporator  H.  This  is  of  similar  construction  to  the  vacuum 
evaporators  used  for  concentrating  soap  makers"  crude  glycerine,  except  that  no  salt- 
discharging  det.ails  are  fitted  to  it.  The  vapour  drawn  off  from  the  evaporator  down 
the  pipe  J  bj'  the  vacuum  pump  L  is  condensed  by  the  water  injector  K  and  is  sent 
as  distilled  water  into  the  store  tank  A.     Storage  tanks  for  the  partially  concentrated 


U-2      THE  PRODrCTIOX  AXD  TREAT>rENT   OF  \-EGETABLE  OILS 


GLYCERINE  RECOVERY  AND  REFINING  AND  SPLITTING  OF  OILS     143 


144      THE  PRODUCTION  AXD  TREATMENT   OF  \'EGETABLE  OILS 

glycerine  drawn  from  the  evaporator  are  indicated  at  yi,  M.  In  these  the  glycerine 
is  allowed  to  settle  and  deposit  any  sediment  it  may  hold.  The  partially  concentrated 
glycerine  may  be  returned  for  further  concentration  to  the  evaporator,  and  is  then 
finally  discharged  at  Q.     P  is  a  sampling  cock. 

Glycerine  Refining. 

The  ciiide  glycerine  recovered  from  soap  makers'  lyes  after  concentration  may 
contain  iij)  to  about  S(i  per  cent,  of  pure  gh^cerine.  The  remainder  consists  of,  say, 
10  per  cent,  of  water  and  10  per  cent,  of  salt  and  other  impurities.  The  crude  glycerine 
derived  from  the  autoclave  or  TwitcheU  process  of  splitting  oils  or  fats  contains  on 
the  average  about  85  per  cent,  of  glycerine.  The  remainder  is  largely  water,  but  tliere 
is  also  present  a  considerable  amount  of  organic  and  inorganic  impurities.  To  a 
certain  small  extent  the  crude  glycerine  obtained  by  either  of  these  methods  is  used 
directly  ;  but  for  the  two  chief  outlets  for  the  substance,  namely,  in  the  manufacture 
of  high  explosives  and  in  pharmacy,  it  is  essential  that  the  impurities  and  the  water 
should  be  practically  eliminated.  This  eUmination  is  effected  by  distilling  the  crude 
glycerine  under  vacuum  followed  by  concentration. 

The  refuiing  or  distillation  of  glycerine  is  practically  an  industry  by  itseK.  Usually, 
for  instance,  the  soap  maker  does  not  carry  his  work  beyond  the  stage  of  recovering 
the  crude  glycerine.  This  he  disposes  of  to  the  glycerine  refineries.  Even  some  of 
the  largest  producers  of  crude  glycerine  regai-d  it  as  their  final  market  product,  and 
do  not  attempt  to  refine  it  themselves. 

As  we  have  said  above,  glycerine  distils  mider  atmospheric  pressure  at  29(»°  C, 
and  in  so  doing  siiffers  some  decomposition.  It  camiot  therefore  be  satisfactorily 
distilled  at  ordinary  pressure  bj'  means  of  dry,  external  heat.  In  practice  the  method 
adopted  is  to  heat  it  in  a  vacuum  by,  and  in  the  presence  of.  superheated  steam. 
The  crude  charge  thus  distils  without  decomposition  of  the  glycerine,  but  the  distillate, 
it  must  be  noted,  is  not  pure  glycerine.  It  consists  of  glycerine  vapour  accompanied 
by  water  vapour,  and  the  vapour  of  any  of  the  impurities  in  the  crude  charge  which 
are  volatile.  Among  the  latter  we  may  include  common  salt,  for  if  this  body  is  not 
actually  volatile  at  the  pressure  and  temperatures  employed  it  would  appear  that  it 
is  carried  over  in  the  distillate  mechanically  with  the  water  vajjour.  and  is  found  in 
the  condensed  distillate.  The  ijrocedure  adopted  for  glycerine  refining  is  to  condense 
the  distillate  in  several  difterent  fractions.  Those  conden.sed  at  the  highest  tempera- 
tures will  be  purest  and  richest  in  glycerine.  As  the  condensing  temperature  becomes 
less  the  percentage  of  glycerine  in  the  condensate  falls,  until  in  the  last  condenser 
the  condensate  consists  of  Uttle  more  than  water  contaminated  with  various  chemical 
impurities. 

The  diagrammatic  an-angement  of  a  glycerine  refining  plant  b}'  Messrs.  George 
Scott  &  8on  is  given  in  Fig.  96,  while  in  Fig.  97  we  give  a  view  taken  in  a  glycerine 
refinery  fitted  up  by  the  same  firm.  Referring  to  the  diagram,  A  is  a  steel  still.  Lito 
this  the  crude  glycerine,  previously  heated  for  preference,  is  introduced  until  the  still 
is  about  half  full.  The  remainder  of  the  charge  is  added  as  the  distillation  proceeds. 
The  still  is  fixed  close  to  a  furnace  B,  the  prime  object  of  which  is  to  fire  the  superheater 
C,  which  supphes  the  still  with  steam.  Incidentally  the  waste  gases  from  the  furnace 
are  used  to  assist  in  maintaining  the  temperature  of  the  still  contents.  The  super- 
heated steam  is  admitted  both  to  closed  and  open  coils  inside  the  stiU.  The  bulk  of 
the  distillation,  however,  is  effected  by  the  steam  issuing  direct  into  the  charge  from 
the  open  coils.  At  D  is  indicated  the  inlet  for  the  charge  of  crude  glycerine,  and  at  E 
is  shown  the  discharge  cock  for  the  '•  still  bottoms,"  that  is,  the  residue  left  after  the 


(iLYCERINK  KECOVEllY  AND  REFIiNINU  AND  SPLITTING  OF  OILS     145 

distillation  is  over.  The  glycerine  and  steam  vaijours  leave  the  still  by  the  pipe  F, 
and  ])ass  into  the  cooling  battery  G.  In  the  case  of  the  plant  re^J resented  in  the 
diagram  the  distillate  can  be  condensed  in  nine  different  fractions.  From  six  to  nine 
fractions  are  usnal.  The  cooling  battery  G  gives  seven  simultaneous  fractions.  It 
consists  of  seven  intermediate  receivers  H  and  seven  final  receivers  J.  The  inter- 
mediate receivers  arc  connected  in  pairs  by  means  of  six  series  of  air-cooled  bent  pipes 
K.     Radiation  and  atmospheric  convection  result  in  the  establishment  of  a  temperature 


Via.  96. — Glycerine  Eefinin''  and  Conceiitratin<?  Plant — Scott. 


gradient  from  pipe  to  pipe  of  the  cooling  battery.  The  most  readily  condensed  portion 
of  the  distillate  falls  finally  into  the  first  of  the  receivers  J,  and  is  practically  pure 
glycerine.  In  each  succeeding  receiver  the  condensate  is  increasingly  rich  in  water 
and  in  volatile  impurities. 

The  residue  of  the  vapoi'ous  distillate  leaving  the  last  pipe  of  the  cooling  battery 
contains  a  small  quantity  of  glycerine,  and  is  passed  into  a  water-cooled  condenser  L. 
In  this  all  the  glycerine  shoidd  be  conden.'^ed  along  with,  of  course,  a  considerable 
amount  of  the  water  vapour.  What  escapes  from  the  condenfser  L  is  passed  into  a 
second  water-cooled  condenser  M.     In  the  ideal  plant  worked  under  ideal  conditions 


146      THE   PRODUCTION   AXD  TREATMENT   OF   VEGETABLE   OILS 

the  condensate  from  M  should  be  pure  water.     If  this  is  attained  then  a  guarantee 
exists  that  none  of  the  glycerine  is  being  lost,  that  all  is  being  recovered. 

In  practice  three  storage  tanks  are  commonly  provided  for  the  reception  of  the 
condensate.  Into  one  of  these  are  run  those  fractions  from  the  cooling  battery  which 
are  adjudged  sufficiently  free  from  chemical  and  other  impurities  to  suit  the  purpose 
for  which  the  glycerine  is  required.  These  mixed  fractions  contain  a  fair  amoimt  of 
condensed  water  vapour  and  have  to  be  concentrated.  Into  the  second  storage  tank 
are  nin  those  fractions  of  the  distillate  which  are  to  be  rejected  because  of  their  impurity. 
These  are  returned  to  the  still  for  redistillation.  Into  the  third  tank  is  run  the  weak 
glycerine  water  derived  from  the  cnndeiiser  L.     This  fraction  may  be  sufficiently  free 


Fig.  97. — Interior  of  a  Glycerine  Refinery. 

from  impurities  other  than  water  to  permit  it  to  be  added  to  the  mixed  fractions  in  the 
first  tank  so  as  to  be  concentrated  along  with  them.  It  may,  however,  be  sufficiently 
impure  to  require  redistillation.  If  its  impurity  is  not  excessive  it  may  be  concentrated 
separate^  and  sold  for  certain  commercial  pui-poses. 

The  still  A,  the  cooling  battery  C4,  and  the  condensers  L,  M  are  maintained  under 
the  proper  degree  of  vacuum  by  means  of  the  pump  N.  The  exhaust  steam  from  this 
pump  is  used  to  assist  in  concentrating  the  selected  fractions. 

The  concentrators  P  P  are  similar  in  principle  to  those  already  referred  to  in  the 
earlier  portion  of  this  chapter.  Thej-  are  provided  with  a  separate  vacuum  pump  Q, 
and  are  fed  with  liquor  through  the  inlets  R.  Steam  is  suppUed  to  them  at  S.  T  T 
indicate  sampHng  cocks.     The  finished  glycerine  is  sent  through  a  filter  press  U. 

The  product  lea\nng  the  filter  press  is  of  a  straw  colour,  and  can  be  used  without 
further  treatment  for  the  manufacture  of  explosives.  Tlio  jiraetice  of  lileaching  the 
glycerine  before  making  use  of  it  in  this  way  is  now  mostly  <li.-*carded,  as  it  adds  little, 
or  nothing  to  the  chemical  puritj-  of  the  material.  For  pharmaceutical  ])urposes 
bleaching  by  means  of  high-grade  animal  charcoal  is  resorted  to.     It  is  usual  to  add 


GLYCERINE  RECOVERY  AND  REFINING  AND  SPLITTING  OF  OILS      147 

the  charcoal  to  tlic  glycerine  while  in  the  concentrator,  and  to  pass  and  repass  the 
liquid  through  the  filter  press  until  the  desired  brilliancy  is  obtained. 

Glycerine  of  dynamite  quality  can  usually  be  produced  from  ciude  glycerine 
obtained  by  splitting  oils  by  one  distillation.  Frequently  one  distillation  is  also 
sufficient  in  the  cause  of  crude  glycerine  from  soap  makers'  waste  lyes  if  the  fractions 
retained  for  concentration  are  carefully  selected.  For  chemically  pure  glyceiine  double 
distillation  is  coninionly  regarded  as  necessary. 

Glycerine  refining  is  a  continuous  process.  A  stoppage  in  the  middle  of  the 
distillation  may  result  in  an  increased  amount  of  impure  distillate,  and  may  even  reduce 
the  total  yield.  In  general,  if  soap  lye  glycerine  is  being  treated  the  still  should  be 
cleared  of  its  "  bottoms  "  at  least  once  a  week.  These  "  bottoms  "  consist  of  a  black, 
tarry  mass  containing  much  common  salt,  and  are  practically  valueless.  In  the 
treatment  of  crude  "  split "'  glycerine  the  still  can  be  run  for  a  fortnight  without  being 
cleared.  The  "  bottoms  "  in  this  case  are  also  of  a  tarry  nature.  They  are,  however, 
free  from  salt,  and  are  emploj'ed  to  some  extent  in  the  manufacture  of  such  commodities 
as  boot  blacking. 


INDEX 


Accumulator  Pumps,  79 

Relict  Valves,  80 
Aocuniulatovs,  78 
Acetylene,  121 
Alum,  135 

Aluminium  Sulphate,  135 
Anglo-American  Oil  Press,  57 
Mill,  73 

Presses,  Limitations  of,  60 
Anglo-American  and  Cage  Presses  in  Combina- 
tion, 75 
Autoclaves,  108,  140 
Automatic  Cake-paring  Machine,  81 
Automatic  Meal  Moulding  Machine,  52 

Bagging,  Press,  50,  54 
Barium  Carbonate,  141 
Benzene,  5,  83,  87,  141 
Blacking,  Boot,  147 
Bleaching  of  Oils,  94,  100 
Glycerine,  146 
Powder,  101 
Blown  Cotton  Seed  Oil,  7 

Rape  Oil,  10 
Boiled  Oil,  6 
Boot  Blacking,  147 
Box  Presses,  57 

Brush  Machine  for  Palm  Nuts,  24 
Butter,  Cocoa,  9,  106 

Fat,  106 

Mace,  106 

Nutmeg,  106 

Cage  Press,  Revolving,  68 

Oil  Mill,  75 
Cage  Presses,  57,  62 

Method  of  Working,  65 
Twin,  66 

Foundations  for,  66 
Cage    and    Anglo-American    Presses    in    Com- 
bination, 75 
Cake  Breaker,  45 

Compound,  45 
Trimming  Machines,  81 
"  Caledonia  "  Dry  Process  for  Palm  Fruit,  24, 

27 
Carbon  Bisulphide,  83 

Tetrachloride,  83 
Castor  Oil,  7,  8,  106 
Seed,  8,  35,  87 

Decorticating,  36,  37 
Preparatorv  Machinerv  for,  39 
Rolls  for,  39 
Separating,  37 
Shelling,  35 
Catalysts,  106,  108 
Cattle  Foods,  84 
Caustic  Potash,  122 

Soda,  99,  122,  135,  136 
Centrifugal  Extractor  for  Foots,  98 
Charcoal,  100 
Chemical  Solvents  for  Oil,  83 


!  Chlorine,  101 
Chloroform,  83 
Chocolate,  9,  107 
Cholesterol,  2 
Cloths,  Filtering,  94 
Cochineal,  2 
Cocoa  Butter,  9,  106 
Cocoa-nut  Oil,  8,  9,  106 

Refinery,  103 
Cocoa-nnts,  13 

Splitting  Machine  for,  13 
Cold  Drawn  Poppy  Seed  Oil,  11 
Rape  Oil,  10 
Pressing,  49 
Colouring  and  Scenting  Soap,  128 

Matter  in  Oils,  93 
Colza  Oil,  10 
Common  Salt,  123,  133 
Compound  Cake,  45 

Lard,  7 
Concentrators  for  Glycerine,  146 
Continuous  Oil  Press,  Lambert's,  72 
Copra,  4,  9,  12,  13,  15,  87 

Crushing  and  Shredding,  16 
Disintegrator  for,  45 
Final  Reduction  Rolls,  18 
Machines  for  Reducing,  1 5 
Preparatory  Machinery  for,  12 
Reduction  Rolls  for,  17 
Cotton  Seed,  4,  12,  86,  87 
Crushing,  33 
Decorticating,  32 
De-linting,  30 
Preparatory  Machinery,  29 
Re-ginning;  39 
Reduction  of,  29 
Oil,  7,  93,  104,  106 
Blown,  7 
Refinery,  101 
Refining,  7 
Crude  Glycerine,  136 

Recovery  of,  1 33 
Crushing  and  Shredding  Rolls,  16 
Crutching  Machine,  124 
Cutting  Machine  for  Soap,  125 

Decorticating  Castor  Seed,  36 
Cotton  Seed,  32 
Deglycerinising  Works,  122,  132 
De-hnting  Cotton  Seed,  30 
Demargarination,  94,  103 
Deodorising  Oil,  100 
Development  of  the  Oil  Press,  56 
Disintegrator  for  Copra,  etc.,  45 
Distillation  of  Glycerine,  144 
Drying  Soap,  125 
Dutch  Stamper  Press,  56 
Dynamite,  133 

Edge  Runners,  41 
Essential  Oils,  1 
Ether,  83 


150 


INDEX 


Ethylene,  SyntLetio,  121 

Evaporators,  Glycerine,  136 

Extracted  Meal,  4,  45,  84 

Extraction  of  Oil  by  t'heniical  Solvents,  83 

Extraction  Plant,  Scott's,  87 

Extractor,  Centrifugal,  for  Foots,  98 

Factory,  Palm  and  Palm  Kernel  Oil.  27 
Fairfax's  Depericarpiug  Machine,  23 
Fat,  Butter,  106 

Definition  of,  3 
Splitting,  140 
Fats,  106 
Fatty  Acid,  93 

Stock,  122,  132 
Acids,  Free,  Removal  of,  from  Oil,  99 
Ferrous  Carbonate,  113 
Fertilisers,  85 
Fillers  for  Soap,  124 
Filter  Cloth  Washing  Machine.  97 
Cloths,  94 

Presses,  94.  96,  100.  104.  Ill,  136 
Output  of,  96 
Final  Reduction  Rolls  for  Copra,  18 
Fixed  Oils,  1 
Flax,  6 
Foots,  98 

Foundations  for  Cage  Presses,  66 
Frames  for  Soap,  124 
Fuller's  Earth,  100.  102 

Furnaces,    Retort,    for   Hvdrogen    Generation, 
115 

General  Arrangement  of  Oil  Mills,  73 
Generation  of  Hydrogen,  113 
Generators  for  Water  Gas,  1 14 
Glycerides.  103 
Glycerine,  10,  93,  122,  132 

Bleaching,  146 

Properties  of.  133 

Refining.  144 
Government  Committee  on  Oil  Seeds,  84 
Grinding  and  Reducing  Mills,  43 

Hard  and  Soft  Oils,  106 
Hardened  Oils,  107 

Linseed  Oil,  112 
Hardening  of  Oils,  106 

Oil,  Factory  for.  108 
Heating  Meal,  46 
Horizontal  Oil  Press.  56 

Seed  Rolls,  39 
Hydraulic  Cake-paring  Machines,  82 
Hydraulic  Meal  Moulding  Machine,  50 
Hydrochloric  Acid,  101,  135 
Hydrogen,  106 

Cost  of  Producing,  120 

Generation  of,  113 

Retort  Furnaces,  115 
Hydrogenation  of  Oils.  106 
Hydrogenising  Mineral  Oils.  121 
Hydrolysis,  22,  93,  140 

Iron  Sulphate,  135 

Kettles,  Meal  Heating.  46 
Soap  Boiling,  123 
Kieselguhr,  108 


Lambert's  Continuous  Oil  Press,  72 
Lane's  Autoclave,  110 

System  of  Generating  Hydrogen,  113 
System  of  Hardening  Oils,  108 
Lanolin,  2 
Lard,  106 

Compound,  7 
Substitute,  7,  93,  102 
Lime  Water,  141 

Limitations  of  the  Anglo-American  Press,  60 
Linde  -  Frank  -  Caro      System     of     Generating 

Hydrogen,  113 
Linolenine,  104 
Linoleum,  6.  10 
Linoline,  104 
Linoxyn,  6 

Linseed.  4,  6,  12.  18,  20.  86.  87 
Oil,  6.  106,  112 

Hardened.  112 
Preparatory  Treatment  of,  18 
Screening.  18 


Mace  Butter,  106 
Machines : — 

Castor  Seed  Decorticating.  36.  37 
Separating,  37 
Shelling,  35 
Cocoa-nut  Splitting,  13 
Copra  Reducing,  15 
Cotton  Seed  Decorticating.  32 

De-linting.  30 
Filter  Cloth  Washing,  97 
Linseed  Screening,  18 
Meal  Moulding,  46,  57 

Automatic,  52 
Hvdraulic,  50 
Oil  Cake  Breaking",  45 
Trimming.  81 
Palm  Fruit  Deperioarping.  23 
Kernel  Breaking.  16 
Kut  Brushing.  24 
Cracking.  25 
Soap  Chipping,  127 
Crutching.  124 
Cutting.  125 
Mining.  128 
Squeezing,  131 
Stamping,  126 
Magnetic  Separator,  13 
Manganese  Dioxide,  101 
Manufacture  of  Soap,  122 
Manures,  8.  85 

Margarine,  3,  7.  9,  93,  102,  107 
Meal,  Extracted.  45 
Heating.  46 
Kettles.  46 

Moulding  Machines.  46.  50.  52.  57 
Tempering.  46 
Metallic  Soaps,  122,  135 
Jlethod  of  Working  a  Cage  Press,  65 
Mill,  Oil,  Accumulators,  78 

Anglo-American,  73 
General  Arrangement.  73 
Pumping  Equipment.  76 
with  Cage  Presses,  75 
Mining  and  Chipping  Soap.  126 
Mineral  Oils,  Hydrogenising,  121 
Moulding  Machine,  Automatic.  52 
Hydraulic,  50 
Machines,  46,  57 


INDEX 


151 


Mucil.age,  93,  94,  99 
Mustard  Oil,  10 

Naphthalene, 141 

Native  Method  of  Treating  Palm  Fruit,  22 

Neat  Soap,  124 

Nickel,  106.  107 

Sulphate,  108 
Nigre,  123 
Nitroglycerine,  133 
Nutmeg  Butter,  106 

Oleic  Acid,  141 
Oloine,  104 

Oil  Cake,  Compound,  45 
Oil-cloth,  6 
Oil,  Definition  of,  3 
Boiled.  6 
Cold  Drawn,  4 
pjSsential,  1 
Fixed,  1 
Hardened,  107 
Hot  Drawn,  4 
Second  Expression,  4,  45 
Turkey-red,  8 
Vulcanised.  6 
Winter.  104 
1)11  Hardening,  106,  107,  108,  112 
Oil  Hardening  Factory,  108 
Oil  Mill  Accumulators,  78 

Anglo-American,  73 
Cage  Press,  75 
Pumps,  76 
Mills,  General  Arrangement,  73 
Oil  Palm,  African,  Fruit  of,  21 
Oil  Press,  Anglo-American,  57 
Box,  57 
Cage  Type,  52,  62 

Foundafons,  66 
Revolving,  68 
Twin,  66 
Working  of,  65 
Development  of  the,  56 
Horizontal,  56 
Lambert's  Continuous,  72 
Oil  Presses,  Anglo-American,  Limitations  of,  60 
Oil  Presses,  Cage  and  Anglo-American  in  Com- 
bination, 75 
Oil  Refining,  93 

Cocoa-nut,  103 
Cotton-Seed,  101 
Palm  Kernel,  103 
Oil.  Splitting  of,  132,  140 
Oils:— 

Castor,  7,  8,  106 
Cocoa-nut,  8,  9,  106 
Colza,  10 

Cotton  Seed,  7.  93,  1U4.  106 
Linseed,  6,  106 
Mustard,  10 
Olive,  8,  93 
Olive  Kernel,  8 
Palm,  9,  22,  106 
Paljn  Kernel,  9,  106 
Poppv  Seed,  11 
Rape,  10,  93,  106 
Soya  Bean,  9,  106,  107 
Sunflower,  10 
Olive  Oil.  8.  93 

Kernel  Oil,  8 


Palladium, 106 

Palm  and  Palm  Kernel  Oil  Factory,  27 

Palm  Fruit,  "  Caldconia  "  Dry  Process  for,  24, 

27 
Palm  Fruit,  Compromise  Process,  23 
Depcriciirping,  23 
Native  Mel  hull,  22 
Preparatory  ^Machinery,  21 
Palm  Kernel  Oil,  9,  106 

Refining,  103 
Kernels,  12,  87 

Disintegrator  for,  45 
Preparatory  Machinery,  21 
Palm  Nuts,  Brushing,  24 
Cracking,  25 
Treatment  of,  25 
Weight  of,  25 
Palm  Oil,  9,  22,  106 
Pabnitine,  103 
Pan,  Vacuum,  102 
Paring  Cakes,  Machines  for,  81 
Petrol,  Synthetic,  121 
Phytosterdl,  2 
Plodder.  131 

Preliminary  Break  ng  Machine,  15 
Preparatory  Machinery  : — 
Castor  Seed,  29 
Copra,  12 
Cotton  Seed,  29 
Linseed,  12 
Palm  Fruit,  21 
Palm  Kernels,  21 
Press  Bagging,  50,  54 

Cake,  4,  85 
Presses,  Filter,  94,  104,  109,  111,  136 
Presses,  Oil.     See  Oil  Presses. 

Stearine,  104 
Poppy  Seed  Oil,  11 
Pumping  Equipment  for  Oil  Mills,  76 
Pumps,  Accumulator,  79 
Purifiers  for  Water  Gas,  114 

Rape  Oil,  10,  93,  106 
Blown,  10 
Cold  Drawn,  10 
Seed,  12,  18,  86,  87 
Receiving  Pans,  49 
Recovery  of  Glycerine,  132 

Plant,  Glycerine,  136 
Reducing  and  Grinding  Mills,  43 
Reduction    Machinery,    some     Special    Forms 

of,  39 
Reduction  of  Cotton  Seed,  29 
Reduction  RoUs  for  Copra,  etc.,  17 

J'inal,  18 
Refinery  for  Cocoa-nut  Oil,  103 
Cotton  Seed  Oil,  101 
Palm  Kernel  Oil,  103 
Refining  Cotton  Seed  Oil,  7 
Glycerine,  132,  144 
Oils  in  General,  93 
Re-ginning  Cotton  Seed,  30 
Relief  Valves,  Accumulator,  80 
Retort  Furnaces,  Hydrogen,  115 
Revolving  Cage  Press,  68 
Rolls  :— 

Castor  Seed,  39 
Copra.  17.  18 
Cot t. in  Seed.  33 
Linseed,  20 


152 


INDEX 


Sapoxificatiok,  123 

Saturated  and  Unsaturated  Oils,  106 

Scenting  and  Colouring  Soap,  128 

Scott's  Extraction  Plant,  87 

Screening  Linseed,  etc.,  18 

Screw  Press,  56 

Second  Expression  Oil,  45 

Seed  Rolls,  Horizontal,  39 

Separator,  Castor  Seed,  37 

Magnetic,  13 
Shelling  Machine  for  Castor  Seed,  35 
Shredding  and  Crushing  Rolls  for  copra,  etc.,  16 
Slabbing  and  Cutting  Soap,  125 
Soap  Boiling.  122 

FUlers,  124 

Frames,  124 

Making,  106,  122,  132 

Powder,  8 

Stock,  99 

Works"  Spent  Lres.  133 
Sodium  Carbonate,  108 

Chloride,  123,  133 
Soft  and  Hard  Oils,  106 
Solvent  Extraction  Plant,  Working  Charges,  92 

Process,  4 
Solvents,  Chemical,  for  Oils,  83 
Soya  Beau  Oil.  9,  106,  107 
Soya  Beans,  87 
Spathic  Iron  Ore.  113 
Spent  Lyes.  Soap  Works',  133 
Splitting  Machine  for  Cocoa-nuts,  13 
Splitting  Oils  and  Fats,  132,  140 
Squeezing  Machine  for  Soap,  131 
Stamper  Press,  Dutch,  56 


Stamping  Soap,  126 
Stearine,  93,  lo3 

Presses,  104 
Still  Bottoms,  144,  147 
Still.  Vacuum,  99. 
Strickling  Boxes,  47 
Sulphuric  Acid.  101 
Sunflower  Oil,  10 
Sweet  Waters,  141 
Svnthetic  Ethvlene,  121 
Petrol,  121 

Tallow,  106 
Tempering  Meal,  46 
Tetrachlorethane,  83 
Toilet  Soap,  126 

Mill,  128 
Treatment  of  Palm  Fruit,  22 
Trimming  Cakes,  Machines  for,  81 
Twin  Case  Presses,  66 
Twitcheii  Process  of  Splitting  Oils,  141 
Turkey-red  Oil,  8 

Ultra-violet  rays.  Bleaching  by,  101 
Unsaturated  Oils",  106 

VACrtJM  Evaporators  for  Glvcerinc,  136 
Vacuum  St  ills,  99,  102 
Vulcanised  Oil,  6 

WiSUTKG  Machine  for  Filter  Cloths,  97 

Watered  as.  113,  114 

Weight  of  Palm  Xuts,  25 

Winter  Oil,  104 

Working  Charges  of  Solvent  Extraction  Plant,?3 


THE  wnrrEPRiiB?  press,  ltd.,  losdos  asd  tosbkipgk 


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